SAN FRANCISCO – Finally, running back Dalvin Cook will make his Dallas Cowboys debut on Sunday against the 49ers.

Cook was signed to the practice squad a week before the season began and waited patiently while the Cowboys' running game faltered. The Cowboys are averaging 77.2 rushing yards per game, the lowest in the NFL, and have gone a franchise-record 20 games without a 100-yard rusher.

On Friday, coach Mike McCarthy said Cook was ready for the opportunity.

In recent weeks, Cook has seen his snaps increase with the first team. A four-time 1,000-yard rusher with the Minnesota Vikings, his career recently stalled after he gained 214 yards in 15 games with the New York Jets last year. He appeared in a playoff game for the Baltimore Ravens and had 23 yards.

The promotion from the practice squad raises questions about how the Cowboys will fill their running back position on game day.

Rico Dowdle leads the Cowboys with 246 yards and Ezekiel Elliott is second with 115 yards, but can the Cowboys add three running backs who don't play on special teams?

They dressed three running backs in four games, but Deuce Vaughn was inactive the last two games. Fullback Hunter Luepke is an integral part of the offense and special teams.

The only time Elliott has been a healthy scratch in his career was when he was rested in the regular season finales before the upcoming playoffs.

The Cowboys also placed tight end John Stephens Jr. on injured reserve Saturday after he tore the ACL in his left knee during Wednesday's practice. Cornerback Amani Oruwariye was signed from the practice squad. He has had no elevation changes in the last three games.