Colts head coach Frank Reich told reporters that the team is "encouraged" about Brissett's MRI results, but added it's too early to determine whether the signal-caller will suit up for Sunday's matchup against the Miami Dolphins.
"We're just going to have to wait until Wednesday to see how it feels," Reich said Monday. "I mean, it's one thing to come in today after the injury and feel a little [better]. I think in his mind he felt a little bit better than he expected to feel today, but that's still a far cry from being able to play the game.
"He's optimistic, but you have to wait until Wednesday, 48 hours to see how it responds to see if you can even start thinking about practicing and wrapping your mind around playing Sunday."
Brissett sustained the injury during the second quarter Sunday when Pro Bowl guard Quenton Nelson was pushed back into the quarterback and stepped on his left leg. He remained on the field in obvious pain for a few minutes before jogging to the sideline with a noticeable limp.
Brissett, who completed 4-of-5 passes for 59 yards prior to the injury, was evaluated in the blue medical tent before briefly putting his helmet on. He later removed it and watched from the sideline for the remainder of the game.
The Colts (5-3) are currently in second place in the AFC South.