Oct. 16, 2004 will forever be remembered as a seminal moment in the history of Barcelona. That was the day that Lionel Messi, a floppy-haired and relatively unknown teenager at the time, made his professional debut for the club in a league game against local rivals Espanyol.

Messi only came on for the final seven minutes, replacing goal scorer Deco as Barca won 1-0 at the Olympic Stadium in the hills of Montjuic. He had little real impact on the game but would go on to make a huge impact on the club.

In the years prior to Messi's debut -- Barca were founded in 1899 and La Liga began in 1929 -- the Blaugrana had won 16 league titles, one Champions League and zero Club World Cups. In the years since, they've won 10 more league titles, been crowned champions of Europe on another four occasions and have lifted the Club World Cup three times. Meanwhile, Messi has been crowned the world's best player on six separate occasions and scored more than 600 goals.

It's a lot to pack into 15 years but by the same token, the time has also flown by. To mark the anniversary of his debut, ESPN writers Jordi Blanco, Moises Llorens and Sam Marsden look back on that day, speaking to those who knew him best at the time and those who were involved in the game.

'I signed him on a paper napkin ... because I couldn't let him get away'

Before Messi made his official debut, he already had caught the eye in a friendly against Juventus at Camp Nou. However, in a world without social media, there wasn't as much expectation as there might have been in the modern era. Just how much did people know about Messi at the time?

MIGUEL ANGEL LOTINA was the Espanyol manager when Messi made his derby against Barca's Catalan rivals. Lotina also has coached Real Sociedad, Deportivo La Coruna and Villarreal, among others, and is currently in charge of Japanese side Cerezo Osaka.

"When I first took over at Espanyol in 2004, [assistant manager] Tintin Marquez spoke to me about Messi. That was the first time I'd really heard of him. He told me he was a really, really skillful player and that he was brilliant in one-on-one situations. On top of that, he also scored lots of goals.

"We wanted to bring him to Espanyol on loan that summer. At the time, he didn't have a Spanish passport and Barca's three non-EU places in the first-team squad were all occupied. Then, around the time we were pushing for a deal, he played the second half of the Joan Gamper trophy against Juventus. He played so well that Barca accelerated the issue with the passport so that they could have him with the first team that season."

CARLES REXACH played 449 matches for Barcelona between 1966-81, the most for a Barcelona player at the time. He was an executive with the club when he signed Messi, on a paper napkin, in 2000. He has always been linked to Barça and served as Johan Cruyff's right-hand man at the time of the so-called "Dream Team." He serves as an adviser to the club president.

"I was in Argentina when I heard about a kid named Messi and I was surprised that they were referring to a 12-year-old boy. At first I thought they were talking about an 18-year-old. Since I was already there [in Argentina], I figured I would go take a look at him and yes, of course he surprised me. He was physically very small, but I could tell he had an uncommon ability, a special instinct.

"Once in Barcelona I decided to sign him on a paper napkin that a waiter gave me because I couldn't let him get away. His father felt that things were not all too clear and told me they would leave. It was then I decided [to sign him] on the fly."

EUSEBIO SACRISTÁN was part of Frank Rijkaard's coaching staff when Messi debuted for Barcelona's first team. He went on to manage Celta Vigo, Girona, Real Sociedad and Barça B, and as a player he was in about 300 games with Barcelona from 1988-95.

"I don't remember exactly the first time I saw him, but I had heard about him and he was summoned several times to train with the first team. I do remember that we were surprised from the start by his daring. It was not only that he had an outstanding quality, but that he used it, and that on the training pitch he was not run over by the more experienced players. He played with an unbelievable ease."

MAXI RODRIGUEZ and Messi have been close friends since they met in Barcelona. The Rosario natives and Newell's Old Boys products shared good times together as one starred with Espanyol and the other rose quickly through the ranks at La Masía.

"I had never heard of him when I was in Rosario, not even when he started playing. When I got to Barcelona I was hearing about this kid from Newell's youth teams who was trying out with Barça. That's when I started to pay attention, and they would tell me from Rosario as well that a kid who was playing really good football was showing big potential at Barça."

"After a few weeks Horacio Gaggioli, his agent at the time, introduced me to him at La Pampa, an Argentinean restaurant in Castelldefels. We were there a good while eating meat and empanadas at this place next to the highway. The truth is we didn't talk much -- we weren't great at conversation -- but it got better after a while. That was in 2002, my first year with Espanyol. Messi was real tiny, and I'm not sure if he knew me from Newell's."

MANEL EXPOSITO, now a coach with Belgian First División A side KAS Eupen, played for Barça B from 2003-05. His time there coincided with Messi's and both debuted with the first team during a 2003 friendly against Porto in Portugal. An injury ended Exposito's time at Barça; he would spend the rest of his playing days with second-tier teams and won an AFC Champions League trophy with Auckland City in New Zealand before retiring in Belgium.

"We had practiced together a couple of times when they called us up for the friendly in Porto in November 2003, and I remember 15 minutes [of action] being more than enough time for him to exceed his potential. We hardly spoke to one another throughout the entire trip because he was the youngest of the five of us who were called up. Looking back, I get the sense that what was meant as a reward or opportunity for us to shine, for him it was just that one thing: the opportunity of a lifetime, the moment in which he would shock the world. That's where we started to see what he would become.

"It left an impact on me because he was a kid playing like a man, someone who would impose his will at practice and leave the bashfulness in the locker room. What stuck out was a focus that was so out of the ordinary for a 16-year-old kid. He was competitive to the max, much more than we were. He was promoted three levels right from the start from the B team, and we weren't surprised when he earned a cap with the first team that year."

HORACIO GAGGIOLI was Messi's first agent and the person who alerted Rexach to the kid from Argentina. He still preserves, in a safe, the napkin on which the first contract was signed by Messi, Rexach and Gaggioli himself.

"As soon as I went to the airport to pick up Messi and [his father] Jorge, I thought that my colleagues in Argentina had fooled me. The kid was so small, with the thinnest legs you could imagine. Despite all of that and despite the stress we felt at the time, being so tired because of the long trip and jet lag, Messi played a training match the very next day between the Children A and Children B sides. He killed it. He marvelled us all because of the way he moved and how he solved every issue the opponents presented him with."

JORGE MARTIN is the owner of Las Cuartetas in Barcelona, one of the restaurants where Messi used to be a regular before Pep Guardiola changed his diet.

"Messi used to come in regularly with his family. He also would order food from us. Sometimes he would come with [former Espanyol player and fellow Argentine] Pablo Zabaleta, with whom he always had a good relationship. The first time I saw him, he was with Gaggioli, who brought him to the restaurant. He told me the kid was going to be very good, but we never thought he would be this good."

'We found that nothing was too big for him'

Messi was named in a top-heavy squad that featured Ronaldinho, Deco, Henrik Larsson and Samuel Eto'o to face Espanyol. How much of an impression, if any, were people expecting him to have on the Catalan derby?

REXACH: "It was obvious that he was born to play football but I never imagined that he would go on to being the best in the world and today Leo has become the most important player in Barça's history."

SACRISTAN: "[Manager] Rijkaard handled things smoothly without any sense of urgency or burden. That night in the locker room, I vaguely remember that Messi was welcomed with excitement and was supported by the whole group -- especially Ronaldinho, yes, because he saw something special in him and communicated very well with him on the pitch. He [Messi] was very shy off the pitch but that disappeared once on it.

"Messi didn't play much that night, we were winning 1-0 and the substitution for Deco was natural and decided in a few minutes because we hadn't discussed it at halftime. It was anecdotal in a way, but it already left the impression that 'geez, it's what Messi does in training and with the same ease as a workout.' We found that nothing was too big for him."

RODRIGUEZ: "I remember the day of the debut, thinking here are two players from Newell's Old Boys facing off on the pitch face to face in one of La Liga's most important matches."

ALEX GARCIA was the only manager who had Messi for a whole season in Barca's development system. Messi joined late; once that season ended, Messi was already thriving between Youth B, Youth A and the affiliate team. Currently, García is part of the first team's coaching staff and scouts the side's opponents.

"The stars aligned for Messi and the best generation of football players in the sport's history to coincide on the same side. I remember watching a match against Espanyol and I was so excited to see him playing in the First Division; that is the goal of the development system, after all, and that's what all coaches want when kids join Barça. Not all of them make it, but those who do so do it as a sort of reward to everyone else."

MARTIN: "Messi came to Las Cuartetas the same week he made his debut, although I don't think he knew it [was happening at the time]. He used to eat Argentine cuts of beef, although his favorite was the milanesa [breaded beef]. He really liked it. We developed a good relationship, always respectful and mindful of keeping the distance. He gifted us a shirt with No. 30, the same number he wore the day he made his debut. He signed it and we hung it next to those from Zabaleta, Maxi Rodriguez, Javier Saviola, Mauricio Pochettino ..."

'He makes everything look easy'

Wearing No. 30 on his back, Messi came on as a right-winger in the final 10 minutes. He was just 17 years, 3 months and 22 days old when coach Frank Rijkaard brought him on. What was made of his debut?

LOTINA: "Even though it was only a few minutes, you could see he was a different player. But to be honest, you wouldn't necessarily have thought that he would go on to be quite the player he has become. It's not easy to do what he's done in the game. I think he's exceeded all expectations."

REXACH: "His debut was but another step [in the process]. It was a logical path but he basically accomplished everything we could expect and more. I was glad to see him, it was the first step in the process that led up to everything that came after."

SACRISTAN: "'We made a 17-year-old kid play. Fantastic. He has a lot of career ahead, let's go easy.' That would be the summary at the time. I don't know if those were the exact words but something similar.

"Did he exceed what was expected at that time? No doubt about it."

RODRIGUEZ: "I was amazed by his skill and natural ability. He stared down his opponent so naturally and that really caught our attention given his age. Messi was never afraid to face his opponent. He was fast and strong despite being just a boy. Of course, I wasn't aware that Rijkaard had called him up. We had a lot going on at Espanyol. What stood out about Messi then is what stands out now: He makes everything look easy. We speak frequently now to each other but after that match we just greeted each other, that's it."

EXPOSITO: "We had played [a reserves game] the previous Sunday against Huesca at the Mini [Stadium, then home to Barça's reserves] and his call-up to the first team didn't take us by surprise. We were watching on TV and went nuts when he came in for Deco. He came close to beating [Espanyol goalkeeper Carlos] Kameni for a ball in the air, handled a play on the sideline against [Espanyol defender Alberto] Lopo like it was nothing.

"What really grabbed my attention was how he seemed so spectacularly in sync with [Barcelona midfielder Andres] Iniesta, whom we considered an extraordinary player, when they hardly knew each other."

- Marsden: A trip inside the surreal Messi10 circus
- Williams: Arsenal used to be invincible. What happened?
- Ogden: England's trouble with traveling fans

ALEX GARCIA: "The things Messi has achieved is something unique, unthinkable; however, we were already aware that he did things differently compared to everyone else. He exuded such confidence, despite not being tall, and had a unique way of solving problems in matches. That's why, when he debuted against Espanyol, despite the 1-0 advantage, I knew he would take on his marker as soon as he could, and that's what he did."

GAGGIOLI: "Right after the match, we went to La Barca del Salamanca, right on the Port of Barcelona. We also went to some Argentinian restaurants: El Laurel, in downtown, and Las Cuartetas. Our first celebration, if I recall, was with Jorge, his dad, and the two of us.

"Two hours after the match ended, my phone rang. It was a call from Espanyol. They asked me if we were aware that Messi was a Community Player since they were about to denounce us for fielding an ineligible player as he didn't have international clearance. Back then, there could only be three foreign players playing on a team and with Messi, there would have been four. We explained that as soon as he arrived in Barcelona was signed up at the age of 13, Lionel was acting as an assimilated player in development. If he had gotten there at 14, he would have been another foreign player.

"Obviously, [Espanyol] wanted the three points. The story didn't get any bigger, but that was what happened. Despite all explanations, Espanyol filed a complaint anyway; however, it backfired. Later, another team executive who tried to pull that off was Javier Tebas, who is currently La Liga president and, back then, was working as an adviser to several clubs."

Was it universally accepted that a star had just been born?

SACRISTAN: "For me, he has gone way beyond what I could have imagined because guessing the impact he would have was nearly impossible. Leo has gotten better day after day, year after year because at that time, you don't even think about whether he will have that longevity, one he has maintained with a phenomenal regularity for 15 years.

"I don't think there is a high-level athlete like him who has had the endurance to maintain himself above the rest. There is not one like him."

RODRIGUEZ: "After that match, Barcelona wouldn't talk about anything else but Messi. Barça fans were happy; you could tell they were proud to have him. He did everything so naturally. Even though he only faced him for a few minutes, he knew how to play against David Garcia, our left-back. Lopo and [Espanyol defender] Antonio Soldevilla also saw him up close.

"What Messi has achieved over the last 15 years in La Liga is tremendous. He has taken his place among the greatest, beyond goals and assists. Lionel's essence is football, and we should always appreciate the competitiveness he has shown us since Day 1."

GAGGIOLI: "We all saw that Messi was going to be an excellent footballer; however, as time goes on, we have realised he has surpassed any expectations. He is a monster; he is unique. He has won five Ballons d'Or and has been outstandingly dependable. He motivates all other players in trying to reach to his level.

"Rexach was the only person who really wanted him at Barcelona, and he fought to sign him. And look where Messi is now."

With additional reporting by Sam Marsden