The Rocket, however, simply needed a little time to get warmed up.
Clemens escaped that jam by allowing only one run, and went on to complete seven strong innings for his 334th win in the Houston Astros' 6-2 victory over the Rockies on Wednesday.
"It was big to get out of that down just 1-0," Clemens said. "I was very fortunate."
Morgan Ensberg backed Clemens with a three-run homer in the third, and the Astros scored three more runs in the seventh with the help of some terrible Colorado defense to complete a three-game sweep of the Rockies.
The Astros notched their fourth sweep of the year, while the last-place Rockies have lost five in a row and eight of nine.
Clemens (6-3) allowed two runs and five hits, struck out four and walked two, lowering his major league-leading ERA to 1.51 -- the lowest of his 21-year career through his first 15 starts. The Rocket, ninth on the career wins list, has won three consecutive decisions for the first time this season.
"You can't miss opportunities to score like that against him," Rockies manager Clint Hurdle said. "They don't come around very much with him on the mound."
Jason Jennings (4-8) allowed six runs and five hits in seven innings. He struck out five and walked two.
Clemens was off to a surprisingly rough start against one of the league's worst offenses, allowing the Rockies to load the bases with no outs in the second.
J.D. Closser grounded into a double play on the next at-bat, driving in Garrett Atkins from third. Clemens escaped further damage when Jennings flied out to center to end the inning.
"Rocket getting out of that bases-loaded jam with only one run was a big momentum shift, too," Astros manager Phil Garner said. "He was just absolutely fantastic."
Following two quick outs to start the third, Craig Biggio was hit by a pitch and Lance Berkman singled. Ensberg followed with a 404-foot shot to left that bounced hard off the brick wall behind the left-field fence.
Ensberg leads NL third basemen with 17 homers, a year after hitting only 10. He didn't hit a home run last year until July 2.
"I'm constantly making adjustments," said Ensberg, who tied the club mark for homers by a third baseman in the first half of the season. "I'm just doing a better job of identifying pitches."
After Ensberg's homer, Jennings retired the next 11 batters but finally fell apart in the seventh.
Chris Burke singled, Brad Ausmus doubled and Jennings intentionally walked pinch-hitter Orlando Palmeiro to load the bases. Jennings threw a wild pitch that allowed Burke to score from third, and Ausmus scored when Closser threw the ball away into the dugout.
Biggio followed those two gaffes with a run-scoring double to push Houston's lead to 6-2.
Jennings was then replaced by Jay Witasick. Jennings, a 26-year-old Dallas native and former Baylor star, dropped to 0-3 with a 13.79 ERA in three career starts against Houston.
"I just tried to go out and keep it as close as possible with (Clemens) on the mound," Jennings said. "Good teams seem to find a way to win ... we seem to find a way to mess it up."
- Houston has won six in a row and nine of its last 10 against Colorado.
- Biggio was twice hit by pitches, bumping his career total to 266. He needs to be plunked only once more to tie Don Baylor's modern-era mark of 267.
- Rockies OF Brad Hawpe turned 26.
- Colorado dropped to 3-15 at Minute Maid Park, its worst record at any NL park. The Rockies haven't won a series in Houston since April 1995 at the Astrodome.