Clemens struck out a season-high 10 in his 331st career win, pitching Houston past the San Francisco Giants 4-1 on Saturday night.
"They went out and did it. It just shows their persistence," Clemens said.
Clemens (3-1) gave up one run and five hits in eight innings, his longest outing of the season. He walked none and has allowed just seven runs in eight starts this season for a 1.11 ERA.
The Astros scored only 11 runs for Clemens in his first seven starts, and six of those games were decided by one run.
Houston had scored more than two runs for Clemens only twice before this season, and four runs equals the Astros' highest run total for Clemens.
"He had another good night, another fantastic night," Houston manager Phil Garner said. "When Biggio hit that home run and Berkman hit his, there was a big sigh of relief. We all felt it on the bench."
Brad Lidge got three straight outs for his seventh save in eight chances.
"You want to put in a fresh Brad Lidge because it's more important for Brad to get that inning than it is for Roger to finish," Garner said.
It was the 109th time Clemens has struck out 10 or more, third on the career list behind Nolan Ryan and Randy Johnson. The last time Clemens did it was Sept. 24, when he fanned 12 in Milwaukee.
The last time the Rocket went eight innings was Sept. 19, also against Milwaukee.
Clemens also got his sixth hit of the season and is batting .353 (6-for-17), best among Houston pitchers.
"If you get Roger on the mound and you score three or four runs, at that point you've got to think that you've got a good chance to win," Berkman said.
Giants starter Brett Tomko (3-5) gave up four runs and six hits in six innings. He struck out four and walked one. He had won three of his last four starts.
Consecutive homers by Biggio and Berkman put Houston ahead in a three-run sixth.
"I'm frustrated with giving up those home runs. It's pretty simple, that was it, that let them back in the game," Tomko said. "To give us a chance I had to match him and I didn't. That means I had to give up one or none."
San Francisco manager Felipe Alou was impressed with Clemens' variety of pitches.
"He has so many pitches that you have to figure out. He throws splits, sliders, curves, fastballs in and out, he throws everything," Alou said. "He's not like Johnson, who throws a high number of fastballs. He uses different stuff in different zones.
"I've never seen him when he didn't use all of his pitches effectively. He's still a pitcher, he's always been a pitcher," Alou added.
Orlando Palmeiro started things off in the sixth with a single and scored on Biggio's sixth home run of the year, third in three games.
Berkman followed with his first of the season. He was out until May 6 following offseason knee surgery.
San Francisco took a 1-0 lead in the third when Ray Durham
doubled and scored on a double by Jason Ellison. Houston tied it in the fifth when Adam Everett doubled and scored on a single by Brad Ausmus.
Houston is 0-16 when trailing after six innings, 0-17 when trailing after seven and 0-20 when trailing after eight. ... Willy Taveras leads NL rookies with 13 stolen bases. ... San Francisco has had more success with the bases loaded than any team in the NL, with a .444 mark (16-for-36) and five grand slams. The Giants' record for grand slams in a season is seven, accomplished in 1951, 1954, 1970 and 1998.