Having seen off Manchester United, Bayern Munich will be confident but cautious as they look to reach the Champions League final for the first time since winning the competition in 2001.
The German giants have gotten through their previous rounds against Fiorentina and United on away goals in both legs, so will hope to try and keep a clean sheet in their own home game when Lyon visit the Olympic Stadium on Wednesday.
Neither side was fancied for this trophy at either the beginning of the season or the onset of the knockout stages but one of them will be in the final and Bayern will want a strong home result to put them in the driving seat ahead of next week's second leg in France.
Both sides could have done without the publicity surrounding Bayern's Franck Ribery and Lyon's Sidney Govou, with the France pair implicated as witnesses in an underage prostitution investigation in Paris this week.
The clubs are looking to put that on the back burner and concentrate on Wednesday's game, however, with Bayen going into it on the back of a 7-0 hiding of Hannover in the Bundesliga, and Ribery should return after sitting that game out. But fellow midfielder Mark Van Bommel is not available, with Danijel Pranjic his likely deputy.
Diego Armando Contento could replace suspended defender Holger Badstuber, with Ivica Olic set to lead the line once more at the expense of Miroslav Klose and Mario Gomez.
Lyon are taking part in their first ever Champions League semi-final having gotten past compatriots Bordeuax last time out, and having already seen off Real Madrid in the previous round there is little reason for Claude Puel's side to fear anyone.
They came through the second leg of the Bordeux tie without main goalscorer Lisandro Lopez, who was banned, but the dangerous Argentine is back to lead the line, while - like Ribery - Govou should also play.
Midfield ace Jean Makoun has also been passed fit to take part, while fellow midfield man Maxime Gonalons is also available.
However, central defenders Mathieu Bodmer and Jean-Alain Boumsong (both injured) and Dejan Lovren (ineligible) cannot play and right back Francois Clerc will only be risked in an emergency.