Houston, TX (SportsNetwork.com) - Houston Texans quarterback Case Keenum will not play in Sunday's game against the Denver Broncos due to a sprained right thumb, interim head coach Wade Phillips revealed following Wednesday's practice.

Additionally, the team placed starting running back Ben Tate on season-ending injured reserve Wednesday. The fourth-year pro has been playing through four fractured ribs since mid-October, having initially sustained the injury during a loss at Kansas City on Oct. 20.

Keenum hurt his thumb at some point in last Sunday's game at Indianapolis, though he played the entire way in the Texans' 25-3 setback to the AFC South champion Colts. The second-year pro's throwing hand will be in a splint all throughout the week, though Phillips said it is possible he could return for Houston's Dec. 29 season finale at Tennessee.

"His right thumb has some ligament problems," said Phillips. "He has to be in a splint all week."

The injury elevates Matt Schaub, who had lost the starting quarterback job to Keenum following a string of poor performances early in the season, back to the No. 1 role for Sunday's matchup.

Schaub has played in just two games since being benched following Houston's 38-13 home loss to St. Louis in Week 6, completing 29-of-54 passes (53.7 percent) for 353 yards with one touchdown and an interception.

Dennis Johnson will operate as the Texans' starting running back over the final two games with Deji Karim serving as the backup. Jonathan Grimes, signed to the active roster Wednesday in a corresponding move, will be the team's No. 3 back.

Tate accumulated 771 rushing yards and four touchdowns on 181 carries over Houston's first 14 games, while adding a career-high 34 catches totaling 140 yards. He had been working as the Texans' lead back since All-Pro Arian Foster went down with a season-ending back injury last month.

Johnson, an undrafted rookie who began the season on the practice squad, has rushed for 154 yards on 37 carries in seven games.