HOUSTON (AP) -- Adam Wainwright kept bending and cracking the knuckle on his right middle finger, trying to make the pain go away. By the sixth inning, he could hardly grip the ball.
Ryan Ludwick hit a three-run homer, Troy Glaus added a solo shot and Skip Schumaker had a single, double and two-run triple for the Cardinals, who beat the Astros for the ninth time in the last 13 meetings.
Wainwright (6-3) left in the sixth with a sprained finger and said he initially hurt it in pre-game warmups. He said popping the knuckle back into place during the game seemed to be the perfect remedy for a while.
"It sort of was lingering throughout the entire game," Wainwright said. "I felt like it needed to pop or get cracked or something. So I kept cracking it and it felt fine."
Wainwright had a 2-2 count on leadoff hitter Darin Erstad when he signaled to the dugout that he had hurt his finger. St. Louis manager Tony La Russa and head athletic trainer Barry Weinberg came to the mound and La Russa brought in Kyle McClellan to relieve.
"All of a sudden, I threw a curve ball to Erstad and it made a noise," Wainwright said. "I couldn't squeeze the ball after that."
Wainwright threw 88 pitches, giving up two runs and seven hits. He had lasted at least 5 2/3 innings in his previous 13 starts. His finger wasn't swollen after the game and Wainwright was frustrated that he couldn't give the Cardinals' relief pitchers more of a break.
"That was the bad thing about it," he said. "Today was the day I definitely could've saved our bullpen a little bit. We were in need of that. Our whole 'pen has been taxed lately."
The Cardinals' pitching staff has been dealing with injuries all season.
Todd Wellemeyer flew back to St. Louis after Thursday's start in Washington with inflammation in his right elbow and several other pitchers are rehabbing, including Chris Carpenter (elbow) and Jason Isringhausen (hand).
Mark Mulder, who's been out with a left shoulder injury, threw a bullpen session before Saturday's game. La Russa gave no timetable on his return.
Weinberg told Wainwright after the game that he was likely to miss 1-2 days of throwing. La Russa said the Cardinals would be cautious.
"It's enough to concern you," La Russa said. "It's the fingertip on his pitching hand, so it's something to be concerned about."
The Cardinals gave Wainwright all the support he needed in the second inning, scoring seven runs off Shawn Chacon (2-2).
Glaus led off with a 420-foot drive to center, his seventh homer of the season and third in four games. Adam Kennedy walked and Wainwright kept the inning alive with a one-out single.
Chacon intentionally walked Albert Pujols, but Ludwick followed with a drive to left-center for a 7-0 lead.
"He just had no command," Houston manager Cecil Cooper said of Chacon. "Everything he threw was either hanging or over the middle of the plate. You can't pitch like that at this level."
The 7-0 lead was more than enough for Wainwright, who came into the game with a 2.18 ERA in 11 career outings against Houston.
Brad Ausmus singled in the second, but Wainwright struck out the other three batters he faced in the inning. In the third, Kaz Matsui and Tejada singled with one out before Lance Berkman hit into a double play.
"He's got four good pitches he locates," Pence said of Wainwright. "He never leaves it out over the plate. He's got a fastball he can put anywhere he wants."
Chacon lasted five innings and gave up only four hits after the disastrous second.
Pence homered in the fifth. Berkman doubled and scored in the sixth on Michael Bourn's single off McClellan and Pence added an RBI single later in the inning to make it 7-3.
Cooper dropped usual leadoff man Bourn to the No. 7 spot in the order. Bourn came in batting .214 and went 3-for-4. ... RHP Todd Wellemeyer (right elbow inflammation) and OF Rick Ankiel (right knee infection) will be re-evaluated on Monday and the two are expected to rejoin the team for the upcoming series in Cincinnati.