Bayern Munich coach Thomas Tuchel admitted on Tuesday his side "are falling well short of our expectations" after a 1-0 home loss to Werder Bremen at the weekend.

Sunday's loss left Bayern seven points behind Bundesliga leaders Bayer Leverkusen, although with a game in hand.

"We're very positive but we're falling well short of our expectations in matches," Tuchel said ahead of Wednesday's game against Union Berlin.

"We will continue to demand it until it works and we're ready to show the desire to spark our fans. We're below our expectations.

"It's not a case of simply flipping the switch... There's a lot of room for improvement."

Bremen had not beaten Bayern since 2008 before Sunday's victory, a run which included 28 defeats and four draws.

Tuchel had been critical of Bayern's performance in a 3-0 win over Hoffenheim to start the year and doubled down after the Bremen setback, saying the reigning Bundesliga champions "played like it didn't matter".

Xabi Alonso's unbeaten Leverkusen have dropped just six of a possible 54 points this campaign, throwing down the gauntlet to Bayern who have won the past 11 Bundesliga titles.

"It's not easy. We're very aware of the state of play," added Tuchel.

"It's our job and it's my responsibility to influence it."

Bayern play at Leverkusen on February 10.

Wednesday's match against Union was originally scheduled for early December but was postponed due to heavy snow in Munich.

Union, who have drawn three and lost five of their eight meetings with Bayern, sit in 15th, one place and three points above the relegation play-off spot.

Coach Nenad Bjelica said his side was wary of a strong Bayern reaction.

"We wanted to wake Bayern up, but Werder Bremen have done it. That's definitely not ideal," he said.

"They certainly won't allow themselves to perform the same way."