Texans defensive end J.J. Watt left practice on Thursday morning with an elbow injury, the extent of which was not known immediately after practice.
Head coach Gary Kubiak said the injury would have to be evaluated but that he thinks Watt will be ready by Week 1.
"J.J.'s got elbow issue that we've obviously got to evaluate here at lunch time and see what happens," Kubiak said. "I'm trying to smile. I'm concerned until we go find out what's going on. But you know, I don't want to say nothing. It's his elbow, we're gonna take a look at it. Hopefully, everything will be OK."
Watt tweeted on Thursday afternoon that he would, indeed, be healthy enough for the Texans' Sept. 9 regular-season opener against Miami.
"Adversity makes you stronger," Watt said. "I will be on the field against the Dolphins. Better than ever."
Watt, an emerging star who 56 tackles and 5.5 sacks as a rookie last season, is the Texans' fourth starter to go down with an injury in the last five days. Wide receiver Andre Johnson (groin) and cornerback Kareem Jackson (hamstring) have been out since Sunday. Left tackle Duane Brown (ankle) suffered a minor injury on Wednesday morning.
"There's been some scares with some key guys on our football team," Kubiak said. "Hopefully, we work through some of that and be fortunate. We've got a long way to go between now and the time we play. Right now, I don't have any doubt that Andre's going to be there on opening day and Duane Brown's going to be there on opening day and J.J.'s going to be, in my mind, he's going to be there on opening day. That's what's most important."
The 11th overall pick out of Wisconsin in 2011, Watt played his best football in the playoffs. He tied for the NFL postseason lead with 3.5 sacks and had an interception return for a touchdown in the Texans' Wild Card victory over Cincinnati. Defensive coordinator Wade Phillips has said during camp that Watt has Hall of Fame potential.
"J.J. is a big part of our team, big part of our defense," Johnson said. "J.J.'ll be back. From what I'm hearing, it's not nothing season-ending, so he'll be fine. He's a hard worker, and I know he's going to do everything he can to make sure he's back on this field. We still have a lot of time left before the season starts, so that's a good thing. I think he'll be out there with us on game 1."
Pro Bowl defensive end Antonio Smith, who predicted last Friday that Watt will become a "megastar" this season, said the entire team was shaken up by Watt's injury.
"I was just concerned that my brother had went down," Smith said. "Seeing him down like that, it kind of took the whole breath out of practice. Everybody was concerned about him, but the trainers took him in, and Kubs (Kubiak) said he's going to be alright. So I'm going to roll with that."
If Watt misses time, defensive end Tim Jamison would likely practice as a starter. Jamison, who went undrafted out of Michigan in 2009, played in all 16 games last season. He had 19 tackles, two sacks and one forced fumble.