Thomas Muller will be involved for Bayern Munich against Cologne, Hansi Flick has confirmed, as the reigning Bundesliga champions aim to get their title defence back on track.

Muller tested positive for COVID-19 while away with the squad at the Club World Cup but is now clear of the virus, allowing him to resume training at the club's headquarters on Thursday.

Speaking to the media, Flick confirmed Muller is to be included in the squad for Saturday's game at the Allianz Arena, with the pressure firmly on after two games without a win in the league.

Ahead of the 100th all-time meeting with Cologne, Bayern have already lost twice as many games (two) in Bundesliga action in 2021 as they did across the entire previous year, with RB Leipzig now just two points behind the leaders in the table.

"He will definitely be part of the squad," Flick said of Muller on Friday. "Things went really quickly with him. 

"Yesterday he had a quick session. Obviously he trained at home, as much as he was able and allowed to do. He's the kind of player who has a good foundation, so he will definitely be a part of that [the matchday squad]. 

"I don't know if it will be possible for him to start or come off the bench, we haven't decided that yet." 

After a surprise 3-3 draw at home with Arminia Bielefeld following their return from clinching Club World Cup success in Qatar, Bayern went down 2-1 at Eintracht Frankfurt last weekend.

They were impressive in midweek, however, thrashing Lazio 4-1 in Rome in the first leg of their Champions League last-16 tie. 

"Against Bielefeld and Frankfurt, there were certain scenes we saw that indicated that better things were to come, but we had missed players and had done a lot of travelling," said Flick, who revealed Tanguy Nianzou is expected to be back after the international break in March. "I don't want to use that as an excuse, though.

"It was important for us to play in the Champions League against an opponent we respected. We followed our plan with great discipline, that's what I also expect tomorrow against Cologne.  

"I expect the team to show great willpower and a great willingness to win that game. We want to continue and play the way we did against Lazio, that's our job."

Jamal Musiala scored in the rout of Lazio before announcing his intention to represent Germany, rather than England, at international level. It now remains to be seen if Die Mannschaft coach Joachim Low calls up the teenage forward for the upcoming World Cup qualifiers in March.

"It's his decision," Flick said of the choice made by Musiala, who turned 18 on Friday. "Obviously I'm a bit biased towards German football, so I think it's a good decision for German football.

"I always said there is enough good talent in this country, you don't have to worry about that. You have to make sure they develop well. 

"Now it's up to the coaches of the Germany team. If he's invited to join the national team, then we accept that. I do think that is going to give him a push. On the other hand, we have a lot of internationals in our squad who can offer support to him, so I don't think it will be a problem."