Updated

HOUSTON (AP) — Rookie Tyler Colvin hit a two-run home run, Aramis Ramirez homered and had 2 RBIs and the Chicago Cubs snapped a four-game losing streak with a 8-5 victory over the Houston Astros on Saturday night.

The loss ended Houston's four-game winning streak, tied for its longest this season.

Ryan Dempster (4-5), who had lost five of his last six decisions, allowed six hits and three earned runs over 6 1-3 innings. He struck out seven.

Roy Oswalt (3-8) fell behind early on Ramirez's second inning homer. Ramirez added a run-scoring single in the fourth, and a sacrifice fly by Alfonso Soriano gave Chicago a 3-2 lead after four innings.

Consecutive doubles by Derrek Lee and Marlon Byrd gave Chicago another run in the sixth.

Colvin, making his 15th start this season, hit his sixth homer in the seventh. Koyie Hill extended Chicago's lead with a two-run double in the eighth off Jeff Fulchino.

Jeff Keppinger extended his hitting streak to seven games with his first homer of the season in the third for the Astros. Humberto Quintero homered in the seventh and added an two-run double in the ninth.

Oswalt pitched seven innings and allowed nine hits, six earned runs and had one walk and one strikeout.

Lance Berkman had an RBI single in the first but the lead held only until the bottom half, when Ramirez slugged his 269th career homer over the left-field fence.

Dempster had control problems in the first. He walked leadoff man Michael Bourn, who stole second and went to third on Jeff Keppinger's grounder.

Dempster then went to a 3-0 count against Berkman, who singled up the middle to score Bourn. Dempster had a full count of Hunter Pence before he grounded out to end the inning.

NOTES: Derrek Lee and Alfonso Soriano each need one home run to reach 300. ... Houston has the highest comeback percentage in the majors. They've rallied to win 13 of their 21 victories, a .619 percentage. ... Hunter Pence ranks second in the NL with 12 infield hits. ... Oswalt started his 283rd game as an Astros pitcher, moving him into third place on the all-time list, one more than Nolan Ryan.