MUNICH -- Xabi Alonso and Bayer Leverkusen need to write another remarkable chapter in their recent history if they are to salvage the seemingly lost cause of their UEFA Champions League round-of-16 tie against Bayern Munich after a brutal 3-0 first-leg defeat at the Allianz Arena on Wednesday.

The only good news for the reigning German champions is that achieving the unthinkable has become their thing under Alonso, having claimed their first-ever Bundesliga title last season without suffering a single league defeat. Leverkusen recorded a 3-0 win against Bayern at the BayArena on their way to that title success, and they need the same result again in Tuesday's second leg to keep this tie alive after two Harry Kane goals -- one a second-half penalty -- and a Jamal Musiala strike secured what would appear to be a decisive victory for Vincent Kompany's team.

Everything that could go wrong for Leverkusen did on a humbling night in Bavaria.

Bayern scored early -- Kane headed them into the lead on nine minutes -- and the home side doubled their lead when Musiala pounced on a huge mistake by goalkeeper Matej Kovar, who inexplicably dropped a cross in the six-yard box, with the ball falling to Musiala's feet.

It got even worse for Leverkusen.

Right-back Nordi Mukiele was sent off for two yellow cards on 62 minutes, forcing his side to play with ten men for half an hour. A harsh VAR intervention 12 minutes later resulted in a Bayern penalty -- scored by Kane -- after little more than a two-way wrestling scrap between the England forward and Edmond Tapsoba.

The only thing that went right for Leverkusen was when Joshua Kimmich and João Palhinha wasted clear chances in stoppage to make it 4-0 and banish any hope of a comeback in the second leg.

In Champions League history, only Barcelona have overturned a 4-0 first-leg deficit to win the tie. In 2016-17, Luis Enrique's team gave us "La Remontada" (The Comeback) by beating Paris Saint-Germain 6-1 in Camp Nou after losing 4-0 in Paris in the first-leg of their Round of 16 clash.

That was a Barca team including Lionel Messi, Neymar and Luis Suárez, so anything was possible with that array of talent. Leverkusen aren't quite so well stocked, but Liverpool (against Barcelona in 2018-19), Barcelona (against Roma in 2017-18) and Deportivo La Coruña (against AC Milan in 2003-04) have all fought back from losing a first leg by a three-goal margin to win the tie with a four-goal victory in the return leg at home.

Leverkusen must somehow do the same against Bayern -- a team that is eight points clear of Leverkusen at the top of the Bundesliga this season -- and add their name to the elite group of teams that have pulled off a sporting miracle.

Alonso has his own history of doing that.

The former Bayern and Real Madrid midfielder was part of the Liverpool team that trailed AC Milan 3-0 at half-time in the 2005 Champions League final in Istanbul before levelling the score and winning on penalties. That win has since become known as the "Miracle of Istanbul," so Alonso might yet decide to dig out the tape and show it to his players next week to prove that anything is possible.

"Absolutely," Alonso said when asked about using Liverpool's win as inspiration. "It will take time to analyse and go through this result because we have been beaten well. Everything went against us because of us, bBut it is not over until it is over and, as you said, anything can happen. The mindset has to be that and if there is a chance, we will fight for it.

"We have to fight back. We will learn from this and believe in our return leg. We don't give up so easily. Three goals? You never know. One goal can change anything."

Bayern are strong, however, and they arguably forced Leverkusen into their worst performance under Alonso.

Atalanta shocked Leverkusen with a 3-0 win in last season's UEFA Europa League final in Dublin -- a result that cost Leverkusen an incredible treble without defeat -- but that win was more down to the brilliance on the night of hat-trick hero Ademola Lookman than Leverkusen's shortcomings. Against Bayern, they were outclassed in every department and also had luck go against them.

Don't underestimate this Leverkusen team, though. Alonso has made them German champions and one of the best teams in Europe, so they will still believe next week.

If Leverkusen score first, stand by for fireworks.