Carlos Lee drove in the winning run in the bottom of the ninth inning to lift the Houston Astros to a 4-3 win over the Washington Nationals on Wednesday night.

Lee's single, that flew just over the head of Lastings Milledge, scored Kaz Matsui and gave Houston its fifth straight victory.

Matsui walked and stole second in the ninth before Joel Hanrahan (0-2) intentionally walked Lance Berkman. Jesus Colome came on in relief and Matsui advanced to third on a wild pitch before Lee's hit. Lee also had the game-winning RBIs in Tuesday's win over Washington

Houston closer Jose Valverde (4-1) pitched a perfect ninth for the win.

Ryan Zimmerman had two homers, the second in the sixth inning to tie it at 3. Zimmerman had two homers in the first three games of the season, but had hit just one in the 29 games since.

The Nationals had a chance to take the lead in the seventh, but Michael Bourn's throw from center field to Brad Ausmus beat Wily Mo Pena home and ended the inning.

Astros ace Roy Oswalt allowed six hits and three runs with a season-high nine strikeouts in seven innings. He allowed both of Zimmerman's homers to bring his season total to 11, which ties the major league lead. Oswalt gave up 14 in all of 2007.

Berkman's homer to the left-field Crawford Boxes in the fourth inning was his eighth consecutive hit, tying a franchise record.

Hunter Pence singled before Ty Wigginton was hit by a pitch. Pence stole third base before Wigginton stole second. Oswalt's single to shallow center scored the pair and gave Houston a 3-2 lead.

Oswalt allowed his 10th homer on Zimmerman's two-run shot to right field in the first inning. Oswalt settled down after the home run, and struck out the next six batters before a double by Felipe Lopez with one out in the third. He retired nine of the next 10, before Zimmerman's second homer with one out in the sixth.

Nationals starter Odalis Perez remains winless in eight starts this season. He allowed five hits and three runs in five innings.

Notes:@ The Nationals replaced Matt Chico in the rotation with Mike O'Connor. Chico, who moves to the bullpen, was 0-5 with a 6.87 ERA in seven starts this season. O'Connor, who'll start Saturday, allowed one hit and walked one in the sixth. ... RHP Felipe Paulino, on the 15-day disabled list with a pinched nerve in his arm, has begun a throwing program at Houston's spring training complex in Florida. ... The Astros traded LHP Stephen Randolph from Triple-A Round Rock to Philadelphia on Wednesday for a player to be named later. ... Nationals catcher Paul Lo Duca was injured while batting in the seventh inning and two fans were ejected for yelling at him.