Rookie Houston Texans quarterback Case Keenum takes on the punishing Kansas City Chiefs pass rush in his first NFL start on Sunday afternoon at Arrowhead Stadium.

The third-stringer Keenum will replace beleaguered Matt Schaub, who is out with an ankle injury, but also threw six interceptions during the Texans four-game losing streak. Undrafted after five years at Houston, Keenum threw 40-plus touchdowns three times, including 48 touchdowns and 5,631 yards in his senior season.

Houston could have gone with third-year back-up T.J. Yates, but he fared no better than Schaub, tossing two interceptions in the 38-13 collapse against St. Louis last week.

Linebacker Justin Houston champions the Kansas City pass rush with 9.5 sacks, tied for best in the NFL. Kansas City is also first in the league in total sacks (30) and points allowed per game (10.8).

Jamaal Charles has largely carried the Chiefs offense, rushing for five touchdowns, including two last week in a 24-7 victory over the Oakland Raiders. Kansas City and AFC West rival Denver are the only remaining undefeated teams in the league.

Houston is 25th overall in the league surrendering 121.5 rushing yards a game, and will miss inside linebacker Tim Dobbins, who is listed as out with a hamstring injury. The Texans true strength comes from their top ranked secondary letting up 131.3 yards in the air, with veteran corner Jonathan Joseph totaling a team-high seven passes defended.

Kansas City has been marginally better against the run, letting up 116.0 rushing yards a game. However it’s second ranked pass defense could miss starting free safety Kendrick Lewis, who was listed as questionable after Friday’s practice with an ankle injury. Rookie corner Marcus Cooper could pick up any slack, as he's tied for third in the league with 10 passes defended.

Keenum takes over an offense that’s scored three touchdowns in the last four games, despite possessing prime weapons in running back Arian Foster and receiver Andre Johnson. Foster gained 141 yards on 20 carries against St. Louis, and is third in the NFL with 531 rushing yards. Six-time Pro Bowler Johnson hasn’t scored a touchdown all season when he’s averaged almost eight touchdowns a year.

Though he’s struggled with a 56.5 completion percentage this season, Chiefs quarterback Alex Smith has provided a steady 207.3 passing yards and seven touchdowns to three picks this season. Smith is also the team’s second-leading rusher, averaging 5.1 yards each time he’s ducked outside the pocket.

Point Spread: Kansas City is favored by 4.5 points.

Over-Under: 40 points

Kickoff Time: 4:25 PM Eastern Time 

Where To Watch Online: NFL Game Access

TV Channel: CBS 

Prediction: Kansas City 24, Houston 23