Williams (7-12) allowed six hits and struck out eight—one off his season high—in 6 1-3 innings. The 41-year-old is 3-0 with a 2.05 ERA in his last four starts.
Later, he was shaking his head, wondering how he won it.
“I was wild in the strike zone and missed a lot of spots,” said Williams. “For whatever reason, I was able to weasel my way out of a lot of trouble. I threw a lot of goofy pitches all over the place. I was fortunate.”
Williams came through for a starting rotation stung by recent injuries. Jason Jennings was placed on the disabled list on Tuesday with season-ending elbow surgery and ace Roy Oswalt will miss Thursday’s start with a strained oblique.
“(Williams) has been throwing the ball great for a while now,” said Brad Lidge, who pitched a perfect ninth for his 12th save in 17 chances. “To do it tonight, when we needed a stopper after the last couple of losses, it was huge.”
Lance Berkman added an RBI triple as Houston beat Washington for just the second time in the last nine meetings.
Austin Kearns hit a two-run homer for Washington, which scored 18 runs in the first two games of the series.
Even Williams was surprised the Nationals didn’t produce more runs on Wednesday.
“I gave (the Nationals) a lot of good pitches to hit,” he said. “That’s a very good lineup. I believe if they’d have swung the bats the way they’re capable of tonight, they’d have scored five or six runs easy.”
Nationals manager Manny Acta was impressed at how Williams buckled down when it counted.
“We had some good opportunities against him early in the game,” Acta said, “but when we threatened, he seemed to make his best pitches.”
Nationals starter Mike Bacsik (5-6) gave up three runs and seven hits with four strikeouts in six innings. Bacsik allowed 10 runs over nine innings in his last two starts.
“I didn’t have my best stuff,” Bacsik said. “It wasn’t my worst stuff, but I would just say that I was just OK tonight.”
The Astros hit two triples in the first three innings and each led to a run.
Wigginton, acquired in a trade with Tampa Bay on July 28, led off the fourth with his second home run since joining the Astros and his 18th of the season. Dmitri Young doubled with two outs in the sixth inning before Kearns hit his 11th homer of the season.
Williams walked Brian Schneider with one out in the seventh. Chad Qualls relieved and gave up a single to pinch-hitter Eric Church. But Qualls got Lopez to bounce into a double play to end the threat. Qualls put two runners on in the eighth but struck out Wily Mo Pena. ^Notes: Nook Logan saved a run in the fifth with an acrobatic catch in deep center to rob Berkman of a hit. “Nook nuked him, boy,” Hosuton manager Phil Garner said. “That was as good of a play as I’ve seen in a long time.” … Houston RHP Brandon Backe (right elbow surgery) will make his final scheduled rehab start on Thursday for Triple-A Round Rock. Backe last pitched in the majors on Aug. 18, 2006. … Astros RHP Chris Sampson (right elbow sprain) is scheduled to pitch one inning in relief Thursday, and then two on Monday for Round Rock … Astros RHP Juan Gutierrez is set to make his first big league start Thursday.