Munich - Interim boss Hansi Flick says Thomas Mueller and Javi Martinez will start for Bayern Munich in Wednesday's Champions League tie against Olympiakos as he rings the changes for his first game in charge following Niko Kovac's sacking.

Kovac was dismissed as head coach on Sunday in the wake of Bayern's 5-1 drubbing at Eintracht Frankfurt.

His assistant Flick has been appointed interim coach for Wednesday's European tie at home to Olympiakos and Saturday's league game against Dortmund.

Flick, 54, was called to an emergency meeting by Bayern's bosses on Sunday night and was "honoured" to be asked to take temporary charge.

Now the former Germany assistant coach wants an immediate response from Bayern's stars against Olympiakos.

"The goals we conceded recently were not 'Bayern like'", said Flick in a press conference.

"We trained today like we want to play."

Both Mueller, 30, and Martinez, 31, mainly started on the bench under Kovac, but Flick wants to utilise the experience of the veterans, who helped Bayern win the 2013 treble of Champions League, Bundesliga and German Cup titles.

"Of course, you can't change everything immediately, but it's also about the selection with perhaps one or two tactical changes," said Flick.

"Javi Martinez and Thomas Mueller will play," he added with Martinez to start at centre-back.

"Niko appreciated Thomas as a player, he (Mueller) is important for the club and has won everything. He can sweep the team along and lead them.

"The team needs to be active and take the initiative, we need to show the quality we have in the squad.

"That goes for every individual player - not just (captain) Manuel Neuer or 'Lewy'", he added with striker Robert Lewandowski having scored a phenomenal 20 goals in 16 games so far this season.

Group B leaders Bayern host bottom side Olympiakos at the Allianz Arena with a fourth straight Champions League win in their sights after beating the Greek side 3-2 in Piraeus a fortnight ago.

Bayern already have one foot in the knock-out phase as they currently sit five-points clear of second-placed Tottenham, who they host in December having routed them 7-2 in north London last month.

However, all is not well behind the scenes at the Bavarian giants, who have won just three of their last six games in all competitions.

Following Sunday's upheaval, ex-Bayern and West Germany defender Andreas Brehme says the Bayern squad "let Kovac down" with a series of lacklustre recent performances, sentiments echoed by midfielder Joshua Kimmich, who says the players must step up.

"It's not so easy for Hansi, he hasn't had much time," said Kimmich.

"The main responsibility now lies with us players.

"We have to pull ourselves together.

"There are no alibis for any of us anymore. An excuse from the coach no longer exists."

Bayern now have two tough games before the international break, also hosting second-placed Borussia Dortmund on Saturday in the Bundesliga with defending champions Munich fourth in the table, trailing leaders Borussia Moenchengladbach by four points.

Flick, part of the Germany staff when they won the 2014 World Cup, will remain in charge until a new head coach is named.

Bayern Munich president Uli Hoeness says they expect to name the new boss within three weeks but two potential candidates have already dropped out.

Ajax's Erik ten Hag has stated he will not leave the Dutch side before the end of the season while Sky German reports that Paris Saint-Germain coach Thomas Tuchel has turned down an approach.

Jose Mourinho, Arsene Wenger and Massimiliano Allegri have been mentioned as possible contenders.