Lidge, the former Astros closer who had a perfect season as he helped the Phillies win the World Series last year, blew his league-high 10th save. The walk-off win was Houston's seventh of the season and first since beating St. Louis on July 22.
"The control just wasn't there," said Lidge, who fell to 0-7 with a 7.15 ERA. "I fell behind on the count to a few guys because of it, and obviously when you're falling behind 2-0, 3-0 and 3-1, you're getting into good hitter's counts. It's tough for me, because I feel like [my slider] has come a long way, but it just wasn't there tonight."
Called upon to protect a 4-3 lead, Lidge struck out Hunter Pence, who drove in the Astros' first three runs, to begin the ninth. Geoff Blum drew a walk, and Chris Coste -- a former Phillies catcher -- hit the first pitch he saw into center to put runners at first and second base.
"He's got two quality pitches and a good fastball," Blum said. "And with that slider, he does a good job of making that thing look like a strike and then it dives out of the zone. So I think the more pitches we can make him throw and wear him down or maybe force him to throw strikes and get back to his heater, the better. We did a good job taking pitches and got some guys on base, which puts pressure on the defense. It just turns out we had some extremely good at-bats that last inning."
Jason Michaels, another former Phillies player, drew a four-pitch walk to load the bases and send the crowd into a frenzy. Lidge, who was the subject of much scorn in Houston despite success early in his career, was booed when he ran out from the visitors' bullpen.
With the crowd on its feet, Michael Bourn hit a grounder to first baseman Ryan Howard, who threw to home plate for a forceout. Bourn, who was in the trade that sent Lidge to the Phillies after the 2007 season, swung at the first pitch after Lidge had thrown four straight balls.
"We had some real good at-bats in that inning, particularly Blum getting a walk and then Coste getting his base hit," Cooper said. "Jason Michaels had a real, real good at-bat to walk, and I think Michael Bourn got a little anxious, a little excited because of the situation and who he was facing and all that and the guy he was traded for. I'm sure he was thinking about all that.
"Kaz had a real good at-bat, and that was the key -- to make him throw strikes. [Matsui] got put in a good situation, and he put a good swing on it."
Matsui, who was 0-for-4 in his first four at-bats, worked the count to 3-1 before stroking a fastball into right-center field. Pinch-runner J.R. Towles scored easily from third, and Michaels came home from second without a throw to give Matsui his first walk-off hit since May 8, 2004, with the Mets.
"The pitcher doesn't want to throw the ball [over the plate], and I figured out where it was going to come and I trusted myself and I was aggressive," Matsui said.
Pence gave the Astros a 3-0 lead by hitting his second two-run homer in as many nights in the second inning and adding an RBI double in the third off Phillies starter Joe Blanton as he extended his hitting streak to eight games. Pence is hitting .407 in that span.
Astros starter Roy Oswalt held Philadelphia to two hits through six scoreless innings. However, he left due to tightness in his lower back with a 3-0 lead and two runners on base with one out in the seventh. Consecutive RBI singles off Tim Byrdak and Jeff Fulchino in a span of three pitches made it 3-2.
Oswalt, who tied a season high with eight strikeouts, said he was pitching with flu-like aches, but he doesn't anticipate his ailing back will keep him from making his next start. He missed two weeks with a left lower back strain earlier this season.
"It started getting tighter and tighter, and I went out there in the seventh and it never really loosened up," Oswalt said. "I thought it would be smart to get out of there now without making it go all the way out and maybe missing a start. Hopefully I got out of there in time and I can get back out there."
The Phillies scored two runs on four hits in the eighth against LaTroy Hawkins, with Howard tying the game with a triple and scoring on Pedro Feliz's go-ahead single. That set the stage for Matsui's showdown against Lidge, who saved 123 games for the Astros in six seasons.
"That's the way Kaz swung the bat last year for us," Cooper said. "He was really, really good for us last year. Left-handed, I thought he was real good. This year he's had some struggles left-handed, and I think lately here he's starting to swing much better."