He was sore when he left after five innings, and he was sore the next day. Clemens is scheduled to pitch on Monday against the Cincinnati Reds, but as of Wednesday, there were no guarantees that he will make that start.
Clemens felt the strain as early as the third inning, but manager Phil Garner suspects Clemens did most of the damage while pitching to Jeromy Burnitz in the fourth.
"You can have an awkward moment," Garner said. "He was slipping on the mound a little bit. I don't know if you call it a mild strain. I don't know if that's what you call it. We use the word 'tweak' to cover everything but a pull. Sometimes, in a day or two, it's fine, and you don't feel it anymore."
Assuming Clemens starts Monday, how cautious the Astros are with the right-hander will depend on how he feels that day.
"If he feels OK, and he could very well be fine, no we won't [be extra cautious]," Garner said. "But if he still feels it a little bit, yeah, we'll be a little cautious."
Pettitte long toss: Andy Pettitte is still on schedule to start on Sunday in Milwaukee, which would be his first start since May 18. The left-hander, who skipped his last start because of tightness in his left forearm, threw long toss on Wednesday in preparation for his return to the mound.
Pettitte originally planned to throw his bullpen session on Friday, but the southpaw is thinking about moving that session to Thursday, a scheduled off-day.
Pettitte is confident he'll make his start on Sunday, but he's also expecting to be a little rusty when he does his side work. If he feels some soreness in that respect, it won't worry him.
"I haven't thrown in five days, so I'm probably going to feel terrible anyway," he said. "I'm sure my shoulder and everything will feel a little cranky."
Red eye: Adam Everett, Morgan Ensberg and Jose Vizcaino spent the hours leading up to Wednesday's game trying out a new contact lens made by Bausch and Lomb.
The lenses work as sunglasses for fielders when they play in the glare of the sun during day games. The idea is to eliminate the need for flip-down sunglasses, which can be a nuisance, especially for infielders.
The contacts are a dark red color, which makes the player look like he's straight out of a scene from "The Exorcist." On fair-haired, blue-eyed Everett, his red eyes could be detected from several feet away.
"They're very comfortable," Everett said. "I've worn contacts for about 15 years. These are a little thicker, but your eye adjusts pretty quickly."
Strickland signs: Always looking for ways to improve the bullpen, the Astros signed right-handed pitcher Scott Strickland to a Minor League contract on Wednesday. Strickland, 29, will report to Triple-A Round Rock on Friday.
Strickland pitched in the Major Leagues for five years before undergoing Tommy John surgery in 2003. In 231 relief appearances with the Expos (1999-02) and Mets (2002-03), Strickland was 12-21 with a 3.28 ERA.
"He's a guy that gives you a lot of appearances," said general manager Tim Purupra, noting Strickland made 69 appearances prior to tearing a ligament in his right elbow in 2002. "He's a quality reliever. He has a great arm and is a possibility for us in the bullpen."
Hammy issues: Craig Biggio felt a slight pull in his right hamstring during Tuesday's game, which was partly why Garner replaced him at second base with Eric Bruntlett in the eighth inning.
Biggio felt the hamstring tighten when he had to make an abrupt stop between second and third before returning to second on a play in the fourth inning.
"When I got to third, I felt something and said, 'What happened here?'" he said.
Biggio ran prior to Wednesday's game without any setbacks, and he started Wednesday's game.
Coming up: The Astros will enjoy a scheduled off-day on Thursday before beginning a three-game series against the Milwaukee Brewers at Miller Park. Right-hander Roy Oswalt (5-5, 3.38) will face Brewers lefty Doug Davis (5-5, 4.31) in Friday's series opener.
Alyson Footer is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.