NFL Network cameras showed Marshall sitting in the back of an ambulance at the start of the second half. Marshall was injured in the first half when a defender's knee hit him in the back.
The Bears say Marshall injured his ribs. He posted a message on his Twitter page later Thursday night, saying "I'm good."
After the game, Ian Rapoport reported that Brandon Marshall's season is "in doubt."
Earlier in the game, Marshall reeled in a spectacular tip-drill catch. He caught three passes for 61 yards before he was injured.
Marshall leads the Bears with eight touchdown receptions this season. He is third on the team in receiving yards and fourth in receptions.
- Dan Gartland