Hansi Flick hailed Leon Goretzka's "excellent" three-assist display against Cologne but admitted he was not entirely pleased with Bayern Munich's overall performance in Saturday's 5-1 win.

Bayern put an end to their two-game winless streak in the Bundesliga with a routine victory against their relegation-battling opponents at Allianz Arena to retain a two-point lead on RB Leipzig at the summit.

Goretzka set up goals for Eric Maxim Choupo-Moting, Robert Lewandowski and Serge Gnabry, making it four assists in his last two outings after also teeing up Jamal Musiala's goal in the 4-1 Champions League win at Lazio in midweek. 

The Germany international was singled out for praise by Flick after the win against Cologne, but the Bayern boss acknowledged there is still room for improvement from his side after conceding for the fourth game in a row thanks to Ellyes Skhiri's strike.

"Leon did an excellent job in assisting the goals. That's why he was Man of the Match for me today," Flick said. "We will analyse the game and show it to the team. There were one or two things I didn't like. 

"But we'll go from game to game. That approach worked well last year. What comes out in the end is up to us. If we put in the performances and pick up wins, we can finish top of the league."

Gnabry marked his return from a thigh injury lay-off by scoring twice from his 14 touches of the ball as a second-half substitute, adding to Lewandowski's brace and Choupo-Moting's opener.

Thomas Muller also appeared for the first time since being struck down by coronavirus at the Club World Cup earlier this month and Flick is delighted to have both players fit and available.

"Serge and Thomas were very important to us as substitutes today," he said. "Thomas assisted Lewy [Lewandowski] with his first touch of the game and brought some certainty to our game, which we needed at that point. 

"Serge has scored two goals. Both will be valuable for us in the next games and I'm happy they're back. It's important to be satisfied with the 5-1 scoreline. We deserved the victory even by that margin."

Bayern let Cologne into the game early in the second half before pulling clear with three goals in the final 25 minutes in what was the 100th competitive meeting between the sides.

With his double on Saturday, Gnabry has now scored nine Bundesliga goals against Cologne - more than against any other side in his career - but the attacker agreed with Flick's assessment that Bayern are not quite at 100 per cent.

"When Thomas and I came on, it was a bit tricky for us," he said. "We hadn't been very sharp or dominant. We tried to lift the tempo and immediately made it 3-1. Then it became easier. 

"In the future, we have to make sure we don't have these shaky phases in the game and we come out of the blocks quicker. Of course, opponents will always have a chance, but we have to reduce these spells, then we'll be stronger again."

Bayern Munich returned to winning ways in the Bundesliga as Robert Lewandowski and Serge Gnabry both scored twice in a convincing 5-1 win over Cologne.

After returning to domestic duties following their Club World Cup success in Qatar with a home draw against Arminia Bielefeld, the reigning champions slipped to a 2-1 loss away at Eintracht Frankfurt last weekend.

However, a 4-1 thrashing of Lazio in Champions League action in midweek proved the catalyst for a first league triumph at their Allianz Arena home since January 30.

Lewandowski's first goal helped Bayern ease into a 2-0 half-time lead and while Cologne briefly threatened a comeback, the returning Thomas Muller made an immediate impression off the bench, providing the assist that allowed the competition's leading scorer to take his tally for the campaign to 28.

Like Muller, substitute Gnabry had an impact on his comeback, the Germany international tucking away a pair of routine finishes as the hosts eased clear in the closing stages.

Eric Maxim Choupo-Moting had opened the scoring with his first league goal for the club, heading in an inviting cross from Leon Goretzka, who then went on to set up his side's second before the break.

The midfielder waltzed his way beyond Rafael Czichos before laying the ball off as goalkeeper Timo Horn came towards him, allowing the ever-ready Lewandowski to roll it into the net.

Cologne failed to even muster an attempt as the first half proved to be one-way traffic, yet they were gifted a route back into the game when hesitation between centre-back pairing Jerome Boateng and David Alaba allowed Ellyes Skhiri in to produce a delicate lofted finish over the advancing Manuel Neuer.

The goal caused a brief wobble, yet the 64th-minute arrival of Muller - back after overcoming coronavirus - helped steady Bayern, the substitute teeing up Lewandowski to restore the two-goal cushion with a shot on the turn.

Dominick Drexler hit the post from a tight angle after robbing possession from Neuer before Gnabry's four-minute brace, the second of which was set up by the outstanding Goretzka with another delightful delivery into the area, added a touch of gloss to the final scoreline.

What does it mean? Bayern remain clear at the summit

Bayern's recent blip had allowed the chasing pack – led by RB Leipzig – to close the gap at the top of the table. Flick's side have already lost more Bundesliga games in 2021 (two) than they did across the entirety of the previous year.

This win is therefore most welcome in what has suddenly become a tighter-than-expected title race, but Flick – who made 44 appearances for Cologne during his playing career - will be concerned at the careless defensive lapse that allowed Skhiri to give the visitors a slither of hope.

Duo back to boost Bayern

While COVID-19 had kept Muller away, Gnabry had not featured since the Club World Cup final due to a thigh issue. The latter only had 13 touches during his goalscoring cameo, but the availability of the pair helps add further strength in depth, even if the fixture congestion eases in March.

Defensive cracks raise concerns

Bayern had conceded 31 goals prior to this game, their highest tally through 22 league games in a campaign since 1991-92. The chance of a clean sheet disappeared when Boateng and Alaba dithered over who was going to attack a loose ball on the edge of the penalty area, in the end neither bothering to take control of the situation.

What's next?

Bayern have a rare week between fixtures, giving them time to prepare for the visit of Borussia Dortmund next Saturday. Cologne, meanwhile, will be hosting Werder Bremen the following day.

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."