INDIANAPOLIS — A couple key injured members of the Indianapolis Colts' defense will be closely monitored this week heading into Sunday's 2019 home opener against the Atlanta Falcons.

Head coach Frank Reich said today starting linebacker Darius Leonard has entered the league's concussion protocol; Leonard, according to Reich, developed symptoms after Sunday's 19-17 road victory over the Tennessee Titans.

Top cornerback Pierre Desir, meanwhile, suffered a knee injury against the Titans and did not return.

Leonard had a game-high-tying 10 tackles and a sack in the win over Tennessee. The Colts could use any number of combinations at their three linebacker spots should Leonard have to miss any time; rookies Bobby Okereke and E.J. Speed are possible candidates to fill in at WILL linebacker.

Desir, meanwhile, suffered his injury early in the third quarter while bringing down Titans wide receiver Corey Davis at the Indy 3-yard line. He was originally labeled as questionable to return before being downgraded to out for the rest of the contest, and finished his afternoon with four tackles (one for a loss).

The team mostly utilized rookie Rock Ya-Sin in Desir's place for the rest of the game. The second-round pick out of Temple was already being used the first two weeks of the season as the extra cornerback in the team's nickel package; Quincy Wilson was seen getting those reps for most of the second half on Sunday.

Reich said today it's too early in the process to anticipate when Desir could return.

"Probably not ready to throw it into a category just yet," Reich said. "We'll see how things develop over the next couple of days and hopefully he responds well, but we'll see how it all plays out."