Indianapolis Colts rule out Shaquille Leonard, Tyquan Lewis for Thursday night with concussions play Shaquille Leonard exits Colts game after suffering concussion (0:23) Colts linebacker Shaquille Leonard exits the game after suffering a concussion in the second quarter. (0:23) 12:55 PM ET Stephen HolderESPN INDIANAPOLIS -- The Indianapolis Colts have ruled out two key defenders with concussion symptoms ahead of Thursday night's matchup with the Denver Broncos . All-Pro linebacker Shaquille Leonard and defensive lineman Tyquan Lewis will not play after sustaining concussions in Sunday's loss to the Tennessee Titans , coach Frank Reich said. Asked whether the decision was made independent of the NFL's concussion protocol, Reich confirmed the team made a unilateral decision to keep the players sidelined. "These decisions were already made that they will be out, even if there was some miraculous (recovery)," Reich said. Also, tests on Colts RB Jonathan Taylor 's ankle were negative, and he has a chance to play Thursday night vs. Denver, a source told ESPN's Adam Schefter. Taylor took a hit to the lower leg on the fourth-quarter play on which he fumbled during Sunday's loss to the Titans. He had 20 carries for 42 yards before leaving the game. Leonard suffered the concussion in the second quarter when he collided with teammate Zaire Franklin , taking a shot to the face that left him bloodied. The league is focusing on head injuries after Miami Dolphins quarterback Tua Tagovailoa sustained a concussion and was carried off on a stretcher in last Thursday night's game against the Cincinnati Bengals , four days after exhibiting signs of a possible concussion in his team's previous game. The NFL and NFLPA are expected to announce an update to the league's concussion protocol amid the controversy around the handling of Tagovailoa's injury.