Munich - Bayern Munich are looking to regroup in the Champions League at home to Celtic on Wednesday as Jupp Heynckes coaches his first European game since winning the 2013 final.
The 72-year-old steered Bayern to the Champions League title four years ago by beating Borussia Dortmund at Wembley to complete the treble of European, Bundesliga and German Cup titles in the 2012/13 season.
However, after Carlo Ancelotti was sacked in the wake of Bayern's 3-0 hammering at Paris Saint-Germain three weeks ago, Heynckes came out of retirement to return as head coach until the end of the season.
After four years away from football, Celtic's visit to Allianz Arena is Heynckes' first real test as Bayern look to show a reaction from their thrashing in Paris.
"'Reparation' is a word often used when you have lost a game in the group phases," said Heynckes when asked if Bayern want to atone for the loss.
"I think we simply must have the ambition to reach the next round.
"The team is highly motivated and looked good in training, but we know Celtic are a strong and aggressive team."
The veteran head coach insisted the Germans will not underestimate Celtic.
"You can always make the mistake of underestimating a team, but Celtic has been (Scottish) champions six times in a row," added Heynckes.
"They twice held Borussia Moenchengladbach and Manchester City to a draw last season which shows they are competitive."
Bayern's hot-shot striker Robert Lewandowski is in rich form with six goals in five matches at Allianz Arena so far this season.
The Polish star is Bayern's most successful foreign goalscorer, with a total of 24 goals, and has scored 10 times in his last 12 Champions League matches.
He scored in Saturday's 5-0 thrashing of Freiburg in the Bundesliga.
The victory was Heynckes' first match back in charge and left Bayern second in Germany's top competition.
However Bayern have just three points from their first two Champions League games and need a home win to get them back on track in Group B.
"We're always under pressure here, but tomorrow is especially important for us," said Bayern defender Jerome Boateng.
"After a defeat in the Champions League, we want to answer with a win."
Bayern's defensive midfielder Javi Martinez has been ruled out after suffering a shoulder injury in the Freiburg win.
"I am not a fan of playing players who are injured and have agreed with the doctor that he (Martinez) will miss the next two games," said Heynckes.
Alongside Martinez, long-term injury victims Manuel Neuer, Franck Ribery and Juan Bernat will also miss Wednesday's game.
However, Heynckes said midfielder Arturo Vidal could feature despite a leg knock.
Brendan Rodgers' Celtic could throw a spanner in Bayern's works with the Bhoys also on three points having won 3-0 at Anderlecht in their last European match.
Former Liverpool coach Rodgers, 44, has turned around Celtic's away form in Europe since taking charge last year.
They are unbeaten in their last three Champions League games away from Celtic Park with draws last season at Borussia Monchengladbach and Manchester City followed by the 3-0 win in Belgium.
The return fixture against Celtic at Parkhead in Glasgow on October 31 is already reportedly popular with German fans.
Some 34,000 Bayern supporters have applied for some of the 3,200 away tickets at the 60,000-capacity stadium for the return leg in a fortnight.