Mariota ran for two scores, including a 34-yarder, in the first half.
The Titans list him as questionable to return.
He played the entire first half, completing 6 of 10 passes for 96 yards and two interceptions. Andre Hal had both picks for the Texans.
Houston added a touchdown on the first possession of the second half to build a 37-14 lead. During that possession, Mariota headed to the locker room.
Cassel was 1-for-2 for 4 yards on the Titans’ first series of the second half as Tennessee went three-and-out.