Rookie Davis to start at running back for Texans
In another change, free safety Marlon McCree will take Matt Stevens' spot in the lineup. Houston ranks last in the league against the pass.
Davis was drafted out of LSU mostly for his skills as a kick returner and has impressed coaches with his field presence and playmaking ability.
"Domanick Davis has been very productive in the role he's had to this point in time," coach Dom Capers said. "He'll have somewhat of an expanded role, and we expect him to produce the way he has."
Davis, 5-foot-9 and 216 pounds, has 171 yards on 35 carries, and his 13 catches rank fifth on the team.
"I've put a lot of hard work into it, so it's paying off right now," Davis said. "It's just time for me to take it to another level."
Mack is gaining only 2.9 yards per carry, with 73 runs for 211 yards as Houston has started the season 2-3.
Davis will be Houston's fourth starting running back in the franchise's first 22 games. Last season, James Allen and Jonathan Wells had little success; Allen is out of the league, and Wells is relegated to special teams as the fourth-string tailback.
This story is from ESPN.com's automated news wire. Wire index