Running back Arian Foster worked out individually but did not participate in the Texans' practice on Wednesday at the Methodist Training Center.
Foster is recovering from a strained hamstring that sidelined him in the third game of the preseason at San Francisco.
"He went a little harder today in his rehab process," Texans coach Gary Kubiak said. "He was over there working out, and he'll be day-to-day. We'll see where we're at tomorrow, but it looked like he did a little bit more from me watching from afar."
Kubiak said that Foster, who had 231 rushing yards against the Colts in Week 1 last season, has improved every day. He aggravated his hamstring injury Aug. 27.
"If Arian's full speed and can play, we want him to play," Kubiak said. "We need to be at our best to win a football game, but at the same time, we've got to listen to what's going on. As I said all along, the progress has been very good and I know there was more progress today, so maybe this conversation is different tomorrow. I don't know. We'll see."
Foster was unsure on Wednesday afternoon if he'll be able to play on Sunday.
"I don't know," he said in the Texans' locker room. "We're going to take it day-by-day and see how it feels on Sunday. I ran pretty well on it today, as close to full speed as you can get without going full speed, and it felt good... I was cutting. I was running and cutting and frolicking."
Foster said that he could see the decision on his status going right up to game time on Sunday.
"Like I said, I ran on it today and it felt good, but you don't want to push it too fast too soon," he said. "This is a 16-game season, and you don't want to rush back for game one if you're not ready. I plan on being ready, but if it's not ready, it's not ready. So we're just going to take it day-by-day."
With Foster sitting out of practice, Kubiak discussed the Texans' contingency plans with backup running backs Derrick Ward, Ben Tate and Steve Slaton.
"You always prepare for possibly not having a guy," Kubiak said. "That's just the way you prepare, so the reps are going Derrick's way, Tate's way and Steve's way right now. Got to get those guys ready to play, but we'll see where we're at tomorrow and see how (Foster) does."
Offensive coordinator Rick Dennison said that he doesn't think the Texans will have to change their game plan much if Foster can't play. The Texans set franchise records last season with 4.83 yards per carry as a team and 2,042 rushing yards.
"What we do is what we do," Dennison said.
Tate, who's third on the depth chart behind Foster and Ward, was one of the Texans' most impressive players in the preseason. He averaged 7.4 yards per carry on 20 attempts.
"I think guys have confidence in him," Kubiak said. "He came in and played extremely well against New Orleans, did some good things against San Francisco. You never know if a guy's taking care of his business until he gets thrown into the spot. He could very well get thrown in there this week. We'll see."
Dennison also praised Tate, a second-round pick from Auburn in 2010 who missed his entire rookie season with an ankle injury.
"He's done a great job," Dennison said. "He's worked hard at it, so he deserves some reps."
Kubiak said that Slaton was "really pushing" Ward and Tate during training camp before a hamstring injury sidelined him for the entire preseason.
"I think he kind of got lost a little bit because he missed that time, but up until the time he pulled a hamstring, he was excellent through camp," Kubiak said. "It was unfortunate, but I think Steve's come back the right way and Steve's ready to be successful again in this league. You never know when your opportunity's going to come, so I've been impressed with what he's done. I'm glad he's on this football team."