The Colts, according to Reich, will play it by ear in determining if Brissett will play in Sunday's game against the Miami Dolphins (1-7).
"We're going to have to wait until Wednesday and see how it feels," Reich said. "It's one thing to come in [Monday] after the injury. I think in his mind he felt a little bit better than he expected to feel. 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 suffered the injury in the second quarter when guard Quenton Nelson was pushed back into him deep in Pittsburgh territory in Sunday's loss to the Steelers. Brissett remained on the ground for a couple of minutes before jogging to the sideline with a noticeable limp.
Brissett, who was 4 of 5 for 59 yards before the injury, spent an extended amount of time in the medical tent before he put his helmet on briefly, then took it back off and watched the rest of the game from the sideline. He said he had a difficult time making lateral movements on his left knee.
Veteran Brian Hoyer, signed by the Colts after the retirement of Andrew Luck, replaced Brissett and was 17 of 26 for 168 yards and three touchdowns despite not getting any first-team reps in practice this season. Hoyer's biggest mistakes were that he threw an interception that was returned 96 yards for a touchdown by Steelers safety Minkah Fitzpatrick and he fumbled the ball on a strip sack on fourth down.
Hoyer will start if Brissett doesn't play Sunday, and Reich said Chad Kelly, the nephew of Hall of Fame quarterback Jim Kelly, would likely be elevated from the practice squad to the active roster to be Hoyer's backup. Hoyer has started 37 games in his career while playing with New England, Arizona, Cleveland, Chicago, Houston and San Francisco.
"Brian, when you look back at the tape, he played pretty well," Reich said. "Played really well in fact. Obviously the pick-six was the big blemish on the scorecard. He's a smart player. He's really simulated well to the offense. Most of those plays he hasn't gotten reps because he wasn't here for training camp and Jacoby takes all the reps. That's pretty much the standard protocol for all teams. You have to get mental reps. He's a pro, does a good job at that and he's a talented football player."
The Colts (5-3), who had their three-game winning streak end with the loss Sunday, are currently in second place in the AFC South.