Houston, TX -- (Sports Network) - Lance Berkman hit a grand slam as part of an eight-run seventh inning for Houston, which took a 12-4 win over San Francisco in the second of four games with the Giants.

Darin Erstad had two hits, including the go-ahead two-RBI single, and Miguel Tejada added three hits and an RBI as the Astros extended their winning streak to six, tying a season-high.

Roy Oswalt (10-8) won his fourth consecutive decision, throwing seven strong innings. He gave up three runs and 10 hits and three walks, while fanning four in the victory.

Tim Lincecum was throwing a gem before being struck in the right knee by a line drive, forcing him to leave in obvious pain. He threw 4 1/3 innings and gave up two runs -- one earned -- and only one hit while striking out seven and walking two.

Tyler Walker (4-7) failed to record an out in facing two batters, and allowed both to score on one hit to earn the loss.

Fred Lewis went 3-for-5 with a run scored while Randy Winn drove in two runs in the Giants' third defeat in five games.

The Astros took control of the game in the seventh. With one out, Brad Ausmus walked, Hunter Pence singled and Mark Loretta walked to load the bases. Erstad followed with a bloop single to plate two, giving Houston a 4-3 lead.

After Tejada's single re-loaded the bases, Berkman crushed a grand slam -- his 24th homer of the year -- to left to stretch the lead to 8-3.

Ty Wigginton added a two-run homer later in the seventh to cap off the huge inning for the Astros. Pence hit a solo home run in the eighth to make it 11-3. Tejada added an RBI double later in the eighth for Houston's 12th run.

Aaron Rowand's ninth-inning homer gave the Giants their fourth run.

San Francisco got on the board in the second. John Bowker led off with a walk, and Rich Aurilia singled. Emmanuel Burriss followed with a bunt single to load the bases with nobody out. Two batters later, Winn lifted a sacrifice fly to center for a 1-0 lead.

Houston took the lead in the third. Ausmus walked to lead off, and three batters later Erstad doubled to tie the game at one. Tejada appeared to end the inning on a groundball to second, but Burriss couldn't handle it, allowing Erstad to score and give the Astros a 2-1 lead.

The Giants answered back in the fourth. Lincecum singled with two outs and Winn followed with an RBI double to center to make it a 2-2 game. Aurilia's sacrifice fly in the fifth gave San Francisco a 3-2 lead.

Game Notes

The Astros previously won six in a row from April 20-25...Houston leads the season series 5-1, assuring the team of its first winning season against the Giants since 1999...Lincecum leads the majors in strikeouts with 182...Houston's Kazuo Matsui left the game after the second inning with a sore back. He is listed as day-to-day...With the win, Oswalt's career record in August improved to 24-5...Houston's eight-run seventh was the most runs the team has scored in an inning this season...Berkman's grand slam was the fourth of his career.