CHICAGO (CBS) — Coming off their biggest win in six years, the Bears suffered a setback on defense on Monday, when they learned veteran outside linebacker Sam Acho will miss the rest of the season, due to a torn pectoral muscle.

Head coach Matt Nagy announced Acho’s injury at his Monday press conference at Halas Hall, a day after the Bears (3-1) trounced the Buccaneers 48-10, for their third straight win.

Acho’s injury will test the Bears’ depth at linebacker, and will be a blow to their special teams unit, where he was a key player.

Acho, 30, was a starter at outside linebacker for the Bears at 2017, and was set to be a starter again this year until the team traded for three-time Pro Bowler Khalil Mack.

In his fourth season with the Bears, Acho has played in 51 games for Chicago. He was drafted by the Arizona Cardinals in the fourth round of the 2011 NFL Draft.

Bears cornerbacks Prince Amukamara and Marcus Cooper, and rookie wide receiver Anthony Miller also are nursing injuries as the Bears head into their bye week. The team will not practice this week, and will get back to work next Monday, to prepare for their Week 6 game against the Dolphins in Miami.