Houston ? Morgan Ensberg had his best game as a major leaguer on the night the Astros were forced to deal with discouraging news about Jeff Bagwell’s injury.

Shortly after finding out that Bagwell would be out at least three months, Ensberg hit three home runs, and Brandon Backe pitched a four-hitter for his first major-league shutout, leading the Astros to a 9-0 victory over the San Francisco Giants on Sunday night.

“I think it’s going to affect the ballclub a great deal,” Ensberg said. “I think a lot of people don’t understand what Jeff Bagwell’s presence in the lineup means to us.”

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.

“This certainly was my best game in the big leagues. I was getting the right pitches, seeing the ball well and getting the right swing,” Ensberg said. “It was really a fun game.”

Bagwell had a pair of three-homer games in 1999, but he has been robbed of much of his power because of the degenerative shoulder condition and has just three homers. He was placed on the disabled list Tuesday, and the team announced Sunday he would have surgery next month.

Bagwell’s rehabilitation is expected to last three months. In the meantime, the Astros — who entered with an NL-low .243 batting average — could use more performances like Ensberg’s.

“I hope we are a team that can take the momentum from tonight and start winning more games,” Ensberg said. “That’s what this is all about.”

Phillies 4, Reds 3

Philadelphia — Vicente Padilla pitched six scoreless innings for his first win and was backed by solo homers from Chase Utley and Bobby Abreu.

Padilla (1-4) tossed four-hit ball in his longest outing of the season to earn his first win since last Sept. 29. Padilla tied a career high with six walks.

Billy Wagner pitched the final 11/3 innings for his ninth save in 10 chances. The Reds added two runs in the ninth on Sean Casey’s RBI single and a sacrifice fly by Ken Griffey Jr., but Wagner struck out Adam Dunn to end the game with the tying run on first.

Elizardo Ramirez (0-1) worked six innings.

Cardinals 4, Mets 2

New York — Matt Morris (3-0) pitched effectively into the eighth inning, and John Mabry homered and drove in three runs.

Subbing at first base to give All-Star slugger Albert Pujols his first day off this season, Mabry also turned two nifty double plays to snuff out potential rallies.

Reggie Sanders hit his 10th home run. Mike Cameron homered, doubled and scored both runs for the Mets, who lost for the fifth time in seven games following a four-game winning streak.

Morris (3-0) retired cleanup batter Cliff Floyd on a popup with runners at the corners to end the sixth and pumped his fist as he walked off the mound.

Nationals 5, Cubs 4

Washington — Chicago second baseman Neifi Perez’s two errors helped Washington score the go-ahead run in the sixth, and Nick Johnson hit a two-run homer.

Johnson’s homer came in the fifth off Maddux, who walked the preceding batter, Jose Guillen, and complained about the landing area on the pitcher’s mound.

In the past week, Washington has gone 3-3 in one-run games, and is 6-5 overall.

Pirates 4, Brewers 2

Pittsburgh — Daryle Ward homered and drove in two runs, and Dave Williams repeatedly pitched out of trouble.

Ward homered in the second inning and added a run-scoring single in the fifth after Matt Lawton’s leadoff double against Gary Glover (2-2), who saw the Brewers win his last four starts.

D’backs 5, Rockies 4

Denver — Craig Counsell hit his first homer since July, and Brian Bruney converted a rare save opportunity.

Counsell homered off Jason Jennings (1-5) in the seventh for a 4-3 lead. Alex Cintron had an RBI double, one of his two hits, to make it 5-3 in the eighth.

Braves 5, Dodgers 2

Los Angeles — Chipper and Andruw Jones each homered for the second straight game, Tim Hudson pitched six innings, and Atlanta knocked the Dodgers out of first place for the first time since April 28.

Padres 12, Marlins 4

San Diego — Dave Roberts hit a three-run homer, and Brian Giles added a two-run single in a 10-run seventh. The Padres won for the 12th time in 16 games.