He completed the opening frame, but backup Curtis McElhinney was charged with leading the team out of the tunnel to begin the second and remained in net until the horn sounded on a 5-2 loss.
Mike Babcock did not provide a specific update on Andersen's condition after the game, but did reveal that it was the Sabres' team doctor who advised his exit. The Athletic's David Alter notes that Toronto's team doctor did not make the trip to Buffalo.
Andersen had won six of this last eight starts entering Saturday's contest, helping the Maple Leafs grab hold of a top-three seed in the Atlantic Division.
McElhinney had a 4-4-0 record and .923 save percentage in nine appearances before conceding three goals in Buffalo.