Foster, the 2010 NFL rushing champion, 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.
Foster said this week he felt no urgency to hurry back, just so he can play in the first game. A year ago, he rushed for a single-game franchise-record 231 yards and three touchdowns against the Colts in the opener. He reached 100 yards rushing in seven more games in 2010, and finished with 1,616 yards to earn an invitation to the Pro Bowl.
Even without Foster, the Texans routed the Colts 34-7.
Derrick Ward, who averaged 6.3 yards on 50 carries last season, is the No. 2 back on the Texans' depth chart.
However, Ward left Sunday's game with an ankle injury and did not return.
Texans receiver Kevin Walter injured his shoulder and sources told ESPN that Walter broke his shoulder and will miss 10 to 12 weeks.
Walter had one catch for 14 yards before he left the game. He said he would have an MRI exam on Monday.
"I wouldn't say I'm worried about it, because I'm going to treat the heck out of it and be ready to roll as soon as possible," Walter said after the game. "I've never had anything like this before, so it's always a concern."
The team said on Sunday night that both Ward and Walter's injuries were still being evaluated.
For the Colts, quarterback Peyton Manning, who did not travel with the team after having neck surgery, was inactive to end his streak of 227 consecutive starts, including playoffs.
Kerry Collins, signed on Aug. 24, started in Manning's place.
Information from The Associated Press was used in this report.