Ubaldo Jimenez turned in his usual dominant outing and Troy Tulowitzki hit a three-run homer to push the Colorado Rockies past Roy Oswalt and the Houston Astros, 4-0, on Thursday.

Todd Helton added two hits and scored a pair of runs and Brad Hawpe chipped in an RBI for the Rockies, who snapped a three-game slide.

Jimenez (8-1) allowed just one hit and walked two while striking out four in seven scoreless frames. The right-hander induced 13 groundouts against three flyouts in lowering his major league-leading ERA to 0.99.

The 26-year-old, who also leads the majors with his eight wins, has yet to allow more than two runs in a start in 2010, surrendering a total of seven runs in 63 1/3 innings.

Tulowitzki gave Jimenez all the support he would need in the top of the first. Oswalt's error on Carlos Gonzalez's grounder allowed the lead runner to reach in the inning and Helton drew a one-out walk in front of Tulowitzki, who drove a 2-2 pitch deep over the left-field wall.

Oswalt (2-6) was sharp after the first, allowing two hits and no runs over the next five innings. The veteran right-hander finished with eight strikeouts in suffering defeat. Houston has yet to score more than two runs in any of Oswalt's losses.

Hawpe capped the scoring with an RBI single off Gustavo Chacin in the eighth.

Michael Bourn, Tommy Manzella and Humberto Quintero each had a hit for Houston, which has lost six of seven.