Bayern Munich are counting the cost of Wednesday's hard-fought 1-0 win over Union Berlin, with German media reporting midfielders Konrad Laimer and Joshua Kimmich are set for injury layoffs.

Laimer looks set to miss between six and eight weeks with a calf injury, German tabloid Bild reported on Thursday.

Laimer was replaced in the 87th minute of Wednesday's win, which took the German champions to within four points of leaders Bayer Leverkusen.

After the game, coach Thomas Tuchel said he was "worried" about the midfielder's injury.

Laimer told reporters his calf muscle "went crazy and closed up after taking a step."

Bild also reported that Kimmich will miss Saturday's trip to Augsburg with a shoulder injury, joining centre-back Dayot Upamecano, who injured his hamstring in the victory, on the sidelines.

Tuchel said a diagnosis confirmed the tear, telling reporters the France defender would be missing for "weeks not days" with the injury.

The Bayern manager said he felt "a little bit jinxed" by the club's injury misfortunes.

With Min-jae Kim away on Asia Cup duty with South Korea, Bayern only have one fit central defender in Matthijs de Ligt.

Eric Dier, who has arrived from Spurs, can play centre-back and replaced the injured Upamecano at half-time to make his Bayern debut.

Forward Serge Gnabry is also battling to return from a muscle complaint. The Germany forward last played in early December, coming off the bench and playing five minutes before being subbed out with injury.

While the club has not confirmed Gnabry's injury, German media reports the former Arsenal player could be missing until March.