Bayern Munich's German forward Thomas Mueller (left) and Moenchengladbach's Austrian defender Stefan Lainer jump for the ball during the German first division Bundesliga football match Borussia Moenchengladbach v FC Bayern Munich in Moenchengladbach, western Germany on Jan 8, 2021. (WOLFGANG RATTAY / POOL / AFP)

BERLIN - The tense mood at Bayern Munich has rarely been more pronounced than at present, as the 2020 treble winner seems to have lost its confidence after letting in the 24th goal in 15 league matches.

For the first time in a decade, Hansi Flick's team threw a 2-0 lead when losing 3-2 to Moenchengladbach

Ahead of the FIFA Club World Cup and the Champions League matches, coach Hansi Flick faces unexpected difficulties that could put a wrench in the works of the Bavarian's 2020/21 season.

The reigning German champion's tactics are seemingly an open book and reveal considerable weaknesses.

Bayern's defense isn't providing the secure platform for its risky attacking game.

New arrivals and old hands are both a long way off top form.

ALSO READ: Bayern retain top spot with comeback 5-2 win over Mainz

Defense instability

"They caught us with some long balls after we lost the ball and our defense was in disorder," striker Thomas Mueller said.

The central defenders like Niklas Suele, David Alaba, and Jerome Boateng lacked stability and their errors led to goal opportunities for their opponents. The trio also seems to lack speed and a positional sense.

For the first time in a decade, Flick's team threw a 2-0 lead when losing 3-2 to Moenchengladbach.

The last time Bayern conceived so many goals so early in the season was in the 1981/82 Bundesliga season.

"It is far too easy to score goals against us," midfielder Leon Goretzka commented.

Bayern might consider further new signings as target Dayot Upamecano (Leipzig) won't be available before next summer. Bayern sports director Hasan Salihamidzic denied plans to consider winter-transfers and said the squad has the necessary quality.

"We need to solve our problem of shoring up the space behind our defenders," Flick stated.

Bayern Munich's Canadian midfielder Alphonso Davies runs with the ball during the German first division Bundesliga football match FC Bayern Munich v Mainz 05 on Jan 3, 2021 in Munich, southern Germany. (ANDREAS GEBERT / POOL / AFP)

Full and wing back instability

After injuries, Benjamin Pavard (right side) and Alphonso Davies (left) are not in good form compared to last season.

But Bayern's game depends on the defense initiating attacks. Simultaneously, wingers such as Serge Gnabry, Kingsley Coman, Douglas Costa, and Leroy Sane are not meeting expectations.

In the league encounter against FSV Mainz (5-2), Bayern managed to turn the game around after going 2-0 down with the help of midfielder Joshua Kimmich at right-back.

Moving Kimmich to the back is only seen as an exception as Flick made clear that the 25-year-old is vital in midfield where he is an inspirational figure.

READ MORE: Bayern sink Wolfsburg with Lewandowski double, Leverkusen stay top

Reserves lack quality

German record international Lothar Matthaeus assumed that the Bayern's bench is not as well equipped as the national rivals such as Leipzig, Dortmund, and Leverkusen.

As a fact, several new arrivals have fallen far from expectations. Leroy Sane might be the most prominent example in addition to Douglas Costa, Bouna Sarr, Marco Roca, Tanguy Nianzou, and Eric Maxim Choupo-Moting.

On top of that, the unsolved future of defenders such as David Alaba and Jerome Boateng remains a problem. While Austrian international Alaba is rumored to be leaving for either Real or the Premier League, Boateng faces growing difficulties in the twilight of his career.