Texans running back Arian Foster is not sure if he'll be able to play in Sunday's opener against the Colts because of his hamstring injury. Foster hurt his left hamstring early in training camp, then aggravated it in the preseason game in San Francisco on Aug. 27. He's been limited in practice since, and said Wednesday he may not know until just before kickoff if he'll be ready to go. "You can't really expect anything with hamstrings," Foster said. "Just taking it day by day. It's frustrating, but injuries are part of the game. You can't escape them, if you play this game for a long time. You just have to maintain them, and take care of them when they happen."