I'd feel safe goin' with him at least one more week. I think he is a better fit than Bettis against the Titans, anyway. Even if he weren't to get (all of) his via the running game, he should get it receiving.
Zereoue will start in Week 11. Jerome Bettis is expected to return from a knee injury, but his role in the offense will be limited. Zereoue is worth using as a No. 2 Fantasy running back in larger leagues.