Cowboys stalwart Zack Martin out with knee injury

FRISCO, Texas -- Pro Bowl guard Zack Martin has been ruled out of the Dallas Cowboys' matchup against the Indianapolis Colts on Sunday because of a knee injury and will miss a game for the first time in his career. 

Martin aggravated a sprained medial collateral ligament in his left knee during last weekend's win against the Philadelphia Eagles. It was the third time this season Martin went down with that injury during a game, but he had not missed a start. He did not practice this week.

Rookie Connor Williams will replace Martin. He also took over for Martin last week. Williams started the first seven games of the season at left guard but lost that job to Xavier Su'a-Filo after undergoing minor knee surgery in October.

"He did a good job in the [Eagles] game going in there and playing," coach Jason Garrett said of Williams. "I thought he handled that work well. He'll benefit from that experience and then he's come back and had a good week so far."

Martin had started all 77 games of his career from the time the Cowboys took him in the first round of the 2014 draft. He was named a Pro Bowler in each of his first four seasons and was twice named a first-team All Pro.

The Cowboys hope the time off will give Martin a better chance to heal and return as soon as Dec. 23 against the Tampa Bay Buccaneers or at least for a playoff run. With a win against the Colts, the Cowboys will clinch the NFC East for the second time in three years.

Linebacker Sean Lee, who has not played since Nov. 5 because of a hamstring pull, and wide receiver Tavon Austin, who has not played since Oct. 14 because of a groin injury, are listed as questionable for Sunday's game.