Andersen allowed two goals on 16 shots in the first period, which ended with Buffalo leading 2-1 at KeyBank Center.
"Obviously the other team's doctor thought he should come out of the game, so he came out of the game," Toronto coach Mike Babcock said. "So once our doctor has seen him [Sunday] then I'll have a better handle on what's going on and I'll be able to tell you."
Andersen was replaced by Curtis McElhinney, who allowed three goals on 22 shots in his fourth game since Feb. 19.
Toronto has a one-point over the Boston Bruins for third place in the Atlantic Division. The Maple Leafs next play the Florida Panthers at home on Tuesday (7:30 p.m. ET; TSN4, FS-F, NHL.TV).
