Houston, TX (Sports Network) - Carlos Lee singled in Kaz Matsui with the winning run in the ninth inning, boosting Houston to a 4-3 win over the Washington Nationals at Minute Maid Park.

Roy Oswalt drove in two runs for Houston. He did everything but earn the victory, hurling seven innings and yielding three runs on six hits and two walks. Oswalt also struck out a season-high nine batters for the Astros, including eight of the first nine he retired and seven in a row to start. After beginning the campaign with three straight losses, Oswalt is 3-0 in his last five trips to the rubber.

Jose Valverde (4-1) tossed a perfect ninth inning to notch the win, whiffing one in the effort.

Lance Berkman continued his hot hitting, going 2-for-3 with a pair of walks and a solo home run for Houston, which has yet to be defeated in May, having reeled off five consecutive victories to start the month. Over his last three games, Berkman reached base 13 times, including a franchise record-tying eight straight hits.

Matsui, who drew three walks, and stole a pair of bases. Houston has triumphed in eight straight home outings.

Washington starter Odalis Perez lasted five innings and surrendered three runs on five hits and two walks while striking out three. In eight starts this season, Perez is winless, though he has posted four consecutive no-decisions. Joel Hanrahan (0-2) did not allow a hit through 2 1/3 innings of work, but he did issue five walks, and was responsible for the decisive run that scored after Jesus Colome came on in relief.

Ryan Zimmerman belted a pair of home runs, finishing 3-for-4 with three runs batted in for the Nationals, who have dropped back-to-back contests after winning eight of 10. Wily Mo Pena and Felipe Lopez each added a double in defeat.

Despite several threats, the squads remained knotted at three until the bottom of the ninth, when the Astros walked off with the win. Matsui started the stanza with a four-pitch walk, and then proceeded to get into scoring position when he stole second. After Miguel Tejada struck out and Berkman earned a free pass on an intentional walk, Colome took the hill to face Lee, but uncorked a wild pitch that allowed Matsui to move to third. Lee followed by lifting a 1-2 offering deep into center, and Matsui trotted home to escape with the victory.

Though he fanned three batters in the first frame, Oswalt got into trouble between the strikeouts. After Lopez whiffed at strike three, Christian Guzman slapped a base hit to left, and Zimmerman followed by depositing the first pitch he saw over the right field fence for an early 2-0 advantage.

Houston took control in the home half of the fourth, starting with Berkman's lead-off home run to left. After a Lee ground out, Hunter Pence beat out an infield single to third, and Ty Wigginton was hit by a pitch. Brad Ausmus then struck out, but on separate pitches during the at-bat, Pence stole third and Wigginton swiped second.

Perez was clearly not worried about the baserunners, but rather focused on notching the third out, as Oswalt was due up next. However, the opposing pitcher helped himself with a base hit to center that plated both Pence and Wigginton, and the Astros took a 3-2 edge.

The lead did not last long, though, as Zimmerman deadlocked the affair at 3-3 when he dug in at the dish in the sixth and cranked out another homer, this one pulled to left.