A groin injury is troubling the influential 33-year-old playmaker, who missed Lyon's 2-1 win over Nancy in the French league on Saturday. He faces a race against time to be fit for Tuesday's Group F clash at Munich's Allianz Arena against struggling Bayern.
Lyon coach Claude Puel can still call on France striker Karim Benzema to lead the French side's attack. Benzema came off against Nancy with a foot injury but Puel insisted "there will be no problems for him to face Bayern."
Lyon had few problems at home to mid-table Nancy on Saturday with Benzema and Brazilian Fred scoring first-half goals to seal victory. With five wins from six and atop the French league, Lyon are in form and drew their opening Champions League game 2-2 at home to Fiorentina.
Bayern may top the table by virtue of their 1-0 win at Steaua Bucharest, but they have slumped in the Bundesliga where two consecutive defeats have left Jürgen Klinsmann's side ninth in the table.
The defending Bundesliga champions were hammered 5-2 at home by Werder Bremen and were then beaten 1-0 by a poor Hannover side on Saturday which has caused more than a few nervous faces in Bavaria.
"We were totally in control for the first 20 minutes, but we let them seize the initiative with a stupid goal from a free-kick," fumed Bayern manager Uli Hoeneß after his side lost for the first time in Hannover for 20 years. "Thankfully we have our next game on Tuesday against Lyon. We can use it to test ourselves at the European level and hopefully find our rhythm, so we play better in the league than we have done recently."
Bayern coach Klinsmann has been resting his main stars ahead of the Lyon clash and strikers Luca Toni and Miroslav Klose are expected to play with flying Frenchan Franck Ribery back in midfield.
Ribery is short of match fitness after three months out after tearing ankle ligaments playing for France against Italy in Euro 2008 in June and he made his return in the debacle against Bremen just over a week ago.
Bayern captain Mark van Bommel is expected to lead the side, but their are question marks over Michael Rensing - Oliver Kahn's replacement in the Bayern goal - who has made mistakes in the last two games.
But Bayern will need to improve on their recent performances if they are to stay unbeaten at the top of the group.