Cowboys cornerback Anthony Brown tore his triceps during Sunday’s game, coach Jason Garrett said Monday.
Brown will undergo surgery and miss the rest of the season.
Brown played 12 snaps against the Lions, breaking up one pass before leaving in the second half.
Jourdan Lewis will take over full-time in the slot, Todd Archer of ESPN reports, with C.J. Goodwin available to play in the dime package.
The Cowboys could promote cornerback Donovan Olumba from the practice squad but will consider external options before making a final decision on Brown’s roster spot, Garrett said.
Brown, a sixth-round pick in 2016, played 10 games this season and recorded 17 tackles and six pass breakups.
He becomes a free agent in the offseason.
Cowboys right tackle La’el Collins, who played 64 of 74 snaps before leaving with a left knee injury Sunday, has a similar injury to the one from earlier this season, Garrett said.
Collins missed one game with a medial collateral ligament sprain when he originally injured his knee.