Bayern Munich demanded an explanation from Canada team officials on Friday after Alphonso Davies suffered a ligament tear that will see him miss the rest of the season.

Davies was forced off early in Canada's 2-1 win over the United States in the CONCACAF Nations League third-place play-off on Sunday.

The left-back has suffered an anterior cruciate ligament (ACL) tear in his right knee, which rules him out of Bayern's crucial season finale.

Davies has been an integral part of Vincent Kompany's side this season, making 31 appearances across all competitions, whthree goals and three assists. 

"It is bitter for us and the way it happened is just not correct," Bayern sports director Christoph Freund told a press conference. "We want to know what exactly happened."

Freund said Davies had complained of fatigue after Canada's prior game but still played.

"He is the captain, a young man who wanted to help his team, but it was borderline," he added.

"The second issue is the injury after 12 minutes. Then, Phonzy flies back on a 12-hour flight, and we all assume it is not a serious injury, but then we have this.

"That is sloppy. It is not professional, and we need to talk and clear it up. We are the employers, we pay the players, so we will be looking into what happened."

Davies was one of two players, along with Dayot Upamecano, who returned from international duty injured. Upamecano will be sidelined for several weeks with a knee injury.

Bayern currently sit top of the Bundesliga, six points clear of second-placed Bayer Leverkusen, and have a Champions League quarter-final against Inter to come next month, a tie that Upamecano will miss.

Kompany's side have gone two games without a win in the Bundesliga, following up a shock defeat to Bochum with a 1-1 draw with Union Berlin before the international break.

Bayern have dropped five points over the last two matchdays, as many as they let slip in their previous 12 fixtures combined.

However, they have often fared well against St. Pauli, winning eight of their last nine competitive games against them. 

Kompany says his team have enough quality to fill the voids and there will be no excuses made.

"It is a pity, first of all, for Phonzy and Upamecano, who cannot be with us at this crucial period of the season," he said.

"This season, we had to compensate for other absences. Hopefully, it will bring the group tighter together.

"The reaction is what's important. There are no excuses for me. Just to win the next game and keep improving."