HOUSTON – Morgan Ensberg hit three home runs and Brandon Backe pitched a four-hitter for his first major league shutout, leading the Houston Astros to a 9-0 victory over the San Francisco Giants on Sunday night.

Ensberg hit a three-run homer in the first inning off Jeff Fassero, a solo homer off Jeremy Accardo in the fifth, and another solo shot in the seventh off Jason Christiansen in the 11th three-homer game by an Astros player.

The last to do it had been Richard Hidalgo on Sept. 3, 2003, against Colorado.

Backe (3-2) didn’t allow an extra-base hit while throwing 114 pitches in the first shutout by a Houston pitcher since Roy Oswalt against Montreal last Aug. 6. He walked two and struck out six.

The Giants didn’t have a hit until the fourth, when Omar Vizquel led off with a single. The closest San Francisco came to scoring was in the fifth, when Marquis Grissom walked and reached third with two outs on pinch-hitter Michael Tucker’s single. But Backe got Jason Ellison to ground to third.

Fassero (0-1) pitched three innings and gave up five runs and five hits in his second start of the season.

After jumping ahead on Ensberg’s home run in the first, the Astros increased their lead to 5-0 in the third on Craig Biggio’s two-run homer, his seventh of the season and fourth in as many games.

Backe had an RBI single in the fifth after Ensberg’s second homer.

Houston manager Phil Garner missed Sunday’s game with flu-like symptoms. Cecil Cooper assumed his duties.

Notes: Houston’s 5-17 record against the Giants at Minute Maid Park is its worst against any NL team since moving to the park in 2000. …. Fassero is the third-oldest pitcher to start a game for the Giants at 42 years, 125 days. Warren Spahn was is the oldest at 44 years, 156 days in 1965, followed by Danny Darwin at 42 years, 310 days in 1998. … J.T. Snow returned to the Giants lineup after missing eight games with an intestinal disorder. Backe is 7-1 in Minute Maid Park.

AP-ES-05-15-05 2254EDT