Most of the offseason questions surrounding the Houston Texans concerned their defense. A day after the preseason opener, coach Gary Kubiak was more worried about an alarming rash of injuries, mostly on the offensive side.

Backup running back Derrick Ward left Monday night’s 20-16 win over the New York Jets with a concussion, and guards Antoine Caldwell and Kasey Studdard will miss Saturday’s game against New Orleans with serious ankle injuries. Left tackle Rashad Butler was the latest Texan to encounter a hamstring injury, joining running backs Arian Foster, Steve Slaton and Ben Tate.

Kubiak said Ward and Slaton were doubtful to play against the Saints, but said Foster, the NFL’s leading rusher last season, may return to practice on Wednesday. Kubiak said Tate, a second-round pick in 2010, is recovering “very slowly.”

“We’ve got some issues at that position, and at the offensive line position,” Kubiak said.

Rookie linebacker Cheta Ozougwu, the last pick in the draft and a product of nearby Rice, also sustained a concussion in the Jets’ game and spent the night in the hospital. Kubiak visited Ozougwu and his family on Tuesday.

“He was resting and doing fine when I went to see him and his family a while ago,” Kubiak said. “Obviously, he took a pretty good shot, and so it’s going to take some time.”

Kubiak says the growing list of injuries has put him in a bind — he’d love to replenish the roster with new players, but says that would complicate preparations for the regular-season opener on Sept. 11.

“Once you get to this point in training camp, you’ve got to get creative, if you start to have problems like this,” Kubiak said. “You’re three weeks away from putting your team together. Yeah, I’d love to go get 2-3 running backs, a couple of offensive linemen. That sounds easy, but that’s not as easy as it sounds. We’ll have to get creative in what we’re doing going into the New Orleans game.”

The defense got through Monday’s game mostly unscathed, and Kubiak saw obvious progress in the unit’s first game executing coordinator Wade Phillips’ 3-4 scheme.

At the start, all eyes were on Mario Williams, who’s making a much-ballyhooed move from defensive end to outside linebacker in the rebuilt defense. Williams, Houston’s sacks leader in each of the past five seasons, was only on the field for 15 snaps.

“I know Mario is excited with what we’re doing,” Kubiak said. “I talked to him at halftime coming out of the tunnel and he told me that one of the biggest factors in standing up in our stadium with noise and everything was getting off on cadence and coming off the ball quicker as compared to having your hand down and your ear a little closer to the football. I think you’ll see him continue to improve.”

The Texans produced seven sacks in the game, after getting only 30 all of last season. And the Jets’ longest pass play covered only 25 yards, another encouraging sign for a secondary that allowed a league-high 18 receptions covering 40 yards or more in 2010.

“Our total effort on defense across the board, I thought it was exceptional,” Kubiak said. “We got to the quarterback, we made plays on the front end, the back end, the linebackers. The ability to rush the passer is exciting for all of us.”

The Texans have been impressed by the rapid progress of first-round draft pick J.J. Watt, projected to start at defensive end this season. Kubiak said Watt stood out on film from Monday’s game, though he wasn’t credited with any tackles.

“He was very good,” Kubiak said. “He was very active, gets his hands up, and I think he’s going to knock a lot of balls down. He doesn’t play like a rookie; he’s a very mature young man, so we’ll up his reps this week.”

One of the closest competitions at camp is between punters Brett Hartmann and Brad Maynard. Hartmann, a rookie, had a 52-yard punt and also handled four kickoffs. Maynard, entering his 14th season, averaged 38.3 yards on three punts and was the holder for Neil Rackers on two field goal attempts.

Rackers connected on both field-goal attempts, from 47 and 49 yards.

“He’s been consistent,” Kubiak said of Rackers, who won the job from Kris Brown in training camp last year. “He’s come back stronger this year. I don’t know if y’all noticed, he worked really hard on himself this offseason and took care of himself physically.”