Landeskog seemed to have suffered a lower-body injury and went to the dressing room with 4:20 to go in the first period after he took a hit from Sharks defenseman Brad Stuart.
Landeskog immediately left the game and appeared to be favoring his left leg as he limped toward the dressing room.
Moments after Stuart's hit, a fight erupted between him and Colorado defenseman Ryan O'Byrne. Stuart received a five-minute fighting major, and O'Byrne, the instigator, received a total of 19 penalty minutes.
San Jose scored twice after the fight to take a 2-0 lead.