HOUSTON -- Houston Texans coach Gary Kubiak is optimistic Arian Foster will be ready for the regular-season opener after the star running back re-aggravated a hamstring injury in Saturday's preseason game in San Francisco.
Foster, the NFL's leading rusher in 2010, left the field in the first quarter of Houston's 30-7 victory, favoring the left hamstring that he strained early in training camp.
Foster sat out Houston's preseason opener, then rushed five times for 47 yards and two touchdowns in the Texans' 27-14 win over New Orleans on Aug. 20. He was hurt on his eighth carry against the 49ers.
"Looks like we're dealing with the same thing we were dealing with at the start of camp," Kubiak said Sunday. "Hopefully, we can get him back on the rehab train, and get him ready for opening day. He'll be day to day."
Kubiak said head athletic trainer Geoff Kaplan offered a "very positive" outlook for Foster's recovery, though Kubiak stopped short of saying Foster would definitely be healed in time for the Sept. 11 opener against Indianapolis.
"Until he hops back out there, there's a concern," Kubiak said. "But it sounds like we're heading in the right direction."
Kubiak also said All-Pro linebacker DeMeco Ryans will return to practice on Monday. Ryans did not travel with the team to San Francisco because of an elbow injury.
Even without Ryans, the first-team defense played well again on Saturday night, holding the 49ers to three first downs and 50 total yards in the first half. Through three preseason games, the Texans' revamped defense has produced 14 sacks and seven turnovers and limited opponents to 32 percent efficiency on third downs (12 of 38).
Kubiak credits new defensive coordinator Wade Phillips with the progress, but he also sees more individual playmakers than he did last year.
Backup safety Troy Nolan returned an interception 73 yards for a touchdown in San Francisco and outside linebacker Connor Barwin, starting defensive end Antonio Smith and backup Tim Jamison all had sacks.
"It's not like it's one guy having a great preseason," Kubiak said. "It's collectively, as a group, all making plays, just bouncing around."
The Texans play at Minnesota on Thursday before trimming the roster to 53 players. Kubiak will take a close look at his secondary, where he still has 18 defensive backs on the roster.
Cornerback Johnathan Joseph and safeties Danieal Manning and Glover Quin are locks for the starting lineup on opening day. Veteran Jason Allen has been pushing second-year cornerback Kareem Jackson on the other side and Brice McCain and second-round draft pick Brandon Harris will be in the mix in reserve roles.
Beyond that, no spots are guaranteed. Kubiak expects fourth-round draft pick Roc Carmichael to return this week after missing time with a shoulder injury, crowding the depth chart even more.
"That's the place in camp we've held up very good health-wise," Kubiak said. "From a numbers standpoint, we're very heavy at that position and have been throughout camp. If they're all standing on Friday morning, a lot of good football players, so we've got to weed through that. You can only keep so many."
The Texans have developed the opposite problem along the offensive line, the unit hardest hit by injuries in training camp. Guards Antoine Caldwell and Kasey Studdard are out with ankle injuries and tackle Rashad Butler missed the 49ers game with a hamstring injury.
Other than Caldwell, though, the starting offensive front has remained intact and performed solidly in the preseason.
"Our first group's been very consistent," Kubiak said. "We've been fortunate with those five guys. They've played a lot of football together and if they can stay out there together, I think they can be a heck of a group."
Kubiak said Derrick Ward has the edge over former second-round pick Ben Tate for the backup role behind Foster, even though Tate has put up more impressive numbers in the preseason. But Kubiak said he still hasn't made a final decision.
"We're still lining up as Derrick as our No. 2 and Tate as our 3 right now, but there's going to be a lot of football played this week," Kubiak said. "I think they both bring something different to our football team, so I could see us playing three guys on game day. Those things will pan themselves out. Like I said, let's get through Thursday. I hope they're all standing and all healthy. We'll figure out that problem if we have it."