Alonso: Leverkusen must be 'almost perfect' against undermanned Bayern

"To beat Bayern we need a top, top game from us - almost perfect. It would be excellent to celebrate after the game, but we're not there yet," said Alonso.

Alonso, who won the World Cup and Champions League along with several league titles during a glittering playing career for Liverpool, Real Madrid, Bayern Munich and Spain, promised to harness his big-match experience.

"A big game is always special - that mood is there. It's nice that we have the opportunity tomorrow to experience that top atmosphere."

Alonso said his side was wary of Bayern striker Harry Kane, who has scored 24 goals in 20 league games since moving from Tottenham in August.

"With Harry Kane you can see his numbers, he's a top, top striker... but defensively we need to think collectively, not as individuals. That's our idea."

Earlier on Friday, Bayern manager Thomas Tuchel said captain Manuel Neuer, who has not trained with the team this week, was in doubt as he battles to recover from a knee injury.

"Manu will try and take part in the goalkeeper training today," Tuchel told reporters.

"It's Manu so we'll give him until (just before the match) to tell us if he's OK."

Neuer may join Serge Gnabry, Kingsley Coman, Konrad Laimer and third-choice goalie Daniel Peretz on the sidelines, while Dayot Upamecano and Joshua Kimmich will return to the squad after injury layoffs.

Neuer returned in October after almost a year on the sidelines with a broken leg. Tuchel confirmed back-up Sven Ulreich is on standby should Neuer be unable to return.

Alonso's Leverkusen have won 26 and drawn four of 30 games in all competitions this season.

But despite dropping just eight of a possible 60 points in the league, Leverkusen are just two clear of Bayern.

Tuchel said "30 teams have tried and 30 teams haven't managed to beat them."

"It's an outstanding run and they deserve it. They're doing incredibly well, but we're only two points behind."

"It's still early in the season but it's a clear opportunity for us to lay our cards on the table."

Asked about reports that almost 200,000 people had applied for tickets in the 30,000-seat BayArena, Alonso quipped "That's a question for (Leverkusen CEO) Fernando Carro, we need to build the stadium bigger.

"That's incredible. Also when we play away, we see that many fans come - that's almost the most important thing, that we have this connection with the fans who have this joy, and who want to celebrate."