LAS VEGAS -- Terence Crawford dismantled Errol Spence Jr. in a tour de force performance, scoring a ninth-round TKO in the long-awaited superfight to capture the undisputed welterweight championship Saturday night at T-Mobile Arena.

Crawford floored Spence in Round 2 and twice in Round 7, a two-fisted beatdown to wrest away the IBF, WBA and WBC 147-pound titles to go along with his WBO belt.

Crawford, 35, buckled a bloodied and swollen Spence in Round 9 and was unloading unanswered shots when referee Harvey Dock mercifully ended the punishment at 2 minutes, 32 seconds.

Spence, 33, protested the stoppage but appeared to lose every round besides the opening frame.

"Like I said before, I only dreamed of being a world champion," said Crawford, ESPN's No. 1 pound-for-pound boxer. "I'm an overachiever. Nobody believed in me when I was coming up, but I made everybody a believer."

Crawford (40-0, 31 KOs), who is nicknamed "Bud," traveled to Scotland in 2014 to win his first world title, a decision over Ricky Burns at 135 pounds. He went on to win the undisputed championship at 140 pounds and is now the first man to capture all four belts at 147 pounds.

"It means everything because of who I took the belts from," said Crawford, who was accompanied by music superstar Eminem and his seminal hit "Lose Yourself" as he entered the ring.

Crawford was in total control of the bout beginning with Round 2, when Spence was floored for the first time in his career. Crawford used a left hand to Spence's body that set up a southpaw jab for a flash knockdown.

Afterward, Crawford told ESPN's Stephen A. Smith that after Spence connected with a looping overhand left in the first two rounds, he thought to himself, "This is it? ... It's going to be a long night for him."

And it certainly was, though Spence (28-1, 22 KOs) never stopped coming forward behind his steady southpaw jab. He was cut over the right eye in Round 3 and barely landed a punch of consequence the remainder of the bout.

Crawford simply beat Spence to the punch time and again and carved up the Texan with his superior timing, sense of range and tremendous counterpunching ability. Crawford outlanded Spence 185-96 in total punches, including an 87-33 edge in jabs and 98-63 in power punches.

Though he's a smaller man, Crawford entered the ring with a 100% knockout ratio in seven welterweight fights and remained perfect in what was arguably the most important boxing match since Floyd Mayweather defeated Manny Pacquiao in 2015.

"He was the better man tonight," said Spence, ESPN's No. 2 welterweight and No. 4 pound-for-pound boxer. "He was using his jab, and my timing was a little bit off. He was catching me in between shots. ... I make no excuses."

There's a bidirectional rematch clause that Spence can trigger within 30 days of the fight, and he vowed to be "a lot better" the second time around. The winner is able to choose if the return bout takes place at 147 or 154 pounds. Spence said he hopes it will be at 154 pounds.

"Hell yeah, we got to do it again," Spence said. "I'm going to be a lot better, it's going to be a lot closer. It's probably going to be in December because [the rematch is supposed to happen] before the end of the year."

Since Crawford captured the WBO welterweight title in his first fight at 147 pounds in June 2018, a TKO victory over Jeff Horn, there had been calls for a summit meeting against Spence. For years, one impediment loomed large: rival promoters.

Crawford was promoted by Top Rank for years, whereas Spence is aligned with PBC. The companies rarely conduct business with one another, and it was a major stumbling block to the highly anticipated fight.

"They tried to blackball me, they kept me out, they kept me out," Crawford said. "They talked bad about me, they said I wasn't good enough, that I couldn't beat these top welterweights, and I just kept my head to the sky and I kept praying to God that I would get the opportunity to show the world who Terence Crawford is. And tonight, I believe I showed how great I am."

Crawford became a promotional free agent following a 10th-round TKO victory over Shawn Porter in November 2021, paving the way for a potential bout with Spence. The sides engaged in talks for much of last year and were on the verge of completing a deal in September but talks collapsed at the 11th hour.

Crawford went on to score a highlight-reel sixth-round KO of David Avanesyan in December in his native Omaha, Nebraska. Spence, a 33-year-old from the Dallas-Fort Worth area, last fought in April 2022, scoring a 10th-round TKO victory over Yordenis Ugas in Arlington, Texas, to pick up a third welterweight title.

The Ugas fight was Spence's first since he underwent surgery in August 2021 to repair a detached retina. He was set to fight the legendary Pacquiao that month but withdrew from the matchup because of the eye injury. Spence came back better than ever, though, just like he did when he recovered from a serious car crash in October 2019 that threatened to jeopardize his career.

Fourteen months after the accident, Spence routed Danny Garcia via decision. And while many boxers have been forced to retire because of a detached retina, Spence returned from the surgery -- just like Sugar Ray Leonard in the 1980s -- to break Ugas' orbital.

But now Spence will need to search for answers ahead of a likely rematch, while Crawford at long last etched the sort of career-defining victory that had eluded him.

The bout was billed as a battle for pound-for-pound supremacy, a meeting of elite boxers, but it ended up being a rout, with one man clearly levels above the other.

Said Crawford, who is usually stoic: "I'm so mixed with so many emotions I can cry right now."