Oswalt struck out nine, Humberto Quintero homered and the Astros beat Colorado 5-4 Thursday for their third straight victory.
Quintero got three hits and Tommy Manzella drove in a career-high three runs as the Astros won for the ninth time in 12 games.
Oswalt (4-8) is 8-2 in his career against the Rockies, including a one-hitter in Coors Field on Sept. 6, 2008.
"I remember I should have had the no-hitter," Oswalt said. "I should have caught the ball hit by Brad Hawpe."
Oswalt wasn't as dominant this time, but he was sharp enough to keep the Rockies tumbling. He gave up four hits over seven innings and left with a 5-2 lead.
"My ball was moving around that night just like today," Oswalt said. "I was making pitches where I wanted them to be and my four-seam fastball was cutting that night, too."
"We still have confidence," outfielder Carlos Gonzalez said. "We know we're a good team, we just need to prove it."
Quintero led off the fifth with his third home run to give Houston a 3-2 lead.
"He got sloppy in the fifth inning and he got sloppy in the sixth inning and it ended up leading to three more runs," Rockies manager Jim Tracy said of starter Jhoulys Chacin.
The Astros took advantage of Chacin's mistakes, something they've done in their recent winning stretch.
"When Carlos and Lance [Berkman] aren't hitting, people like Q and Manzella are coming through," Houston manager Brad Mills said. "Everybody is pitching in and doing a little bit here and there. And the starters and bullpen are doing better."
Five runs was all the support Oswalt needed. The right-hander struck out the side in the first and was in control except for Colorado's two-run fourth. He allowed two runs and four hits and walked two in seven innings.
With Oswalt out of the game, the Rockies rallied in the eighth. Gonzalez, Helton and Tulowitzki led off with singles against reliever Wilton Lopez to make it 5-3. Gustavo Chacin came on and struck out Hawpe before giving up a single to Ryan Spilborghs to load the bases.
"We had pitches to do some damage with to come back and steal this game and we didn't get it done," Tracy said
Brandon Lyon worked the ninth for his first save.
The Astros jumped ahead in the second inning on Chacin (3-5). With one out, Pence walked and Pedro Feliz reached on third baseman Ian Stewart's throwing error. Quintero's double down the left-field line scored Pence and Feliz came home on Manzella's sacrifice fly to make it 2-0.
Chacin allowed five runs, four earned, and four hits. He struck out eight and walked three in six innings.
The Rockies tied it in the fourth when Helton led off with a single and went to third on Tulowitzki's single, who advanced to second on the throw. Hawpe's ground out to second scored Helton and Tulowitzki scored on Seth Smith's shallow fly to center to make it 2-all.
- Astros RHP Bud Norris (biceps tendinitis) threw a side session Thursday and will pitch a simulated game this weekend.
- Rockies RHP Huston Street (inflamed right shoulder) will throw an inning for Triple-A Colorado Springs on Thursday and Friday.