Houston, TX (Sports Network) - Lance Berkman homered and Roy Oswalt tossed six superb innings before leaving with an injury, as the Houston Astros topped the Los Angeles Dodgers, 4-1, in the opener of a four-game series at Minute Maid Park.

Oswalt (7-8) was cruising, allowing only one run on six hits with no walks and nine strikeouts, but had to be lifted before throwing a pitch in the seventh with a strained right hip. He's listed as day-to-day.

Berkman also walked twice and scored two runs, while Brad Ausmus connected on a two-run single for Houston, which has rattled off three straight wins.

Eric Stults (2-1) surrendered four runs on five hits and three walks over 5 1/3 innings in taking the loss. The left-hander was coming off a shutout of the White Sox in just his second start of the season.

James Loney was 2-for-3 with an RBI, and Andre Ethier doubled and scored a run for Los Angeles, which dropped its second in a row.

The Dodgers opened with a run in the first. Ethier stroked a one-out double to left before Oswalt proceeded to plunk consecutive batters to load the bases. Loney then lofted a sacrifice fly to left.

Berkman tied the game, smacking a two-out home run into the seats in left during the home half of the first.

Houston extended its lead with a three-run fourth. Berkman drew a one-out walk and took third on a Carlos Lee double when the ball scooted by a charging Jason Repko in center field. Stults issued an intentional free pass to Miguel Tejada to load them up and Mark Loretta roped a single to left scoring one. After a force out at home, Ausmus lined a two-run single to center for a 4-1 advantage.

Los Angeles had its best chance to cut into the lead in the eighth off Chris Sampson. Russell Martin started things with a single before Jeff Kent hit into a double play. Loney and Delwyn Young strung together back-to-back singles, putting runners on the corners to end Sampson's night. Wesley Wright came on and got pinch-hitter Andy LaRoche to fly out, ending the threat.

Jose Valverde worked around a one-out single from pinch-hitter Angel Berroa and a subsequent balk in the ninth to earn his 22nd save of the season.