~ A three-run home run in the seventh inning rallied St. Louis to a 3-1 victory.

ST. LOUIS -- Albert Pujols whiffed on his first opportunity to get the St. Louis Cardinals going, striking out on three pitches against Roy Oswalt with two men on to end the fifth inning.

His next time up, he gave the team what it has come to expect -- a go-ahead three-run homer in the seventh to lift the Cardinals over the Houston Astros 3-1 Monday.

"He amazes a lot of people, but to us, it's just Albert," closer Jason Isringhausen said. "We don't know where we'd be without him."

The Cardinals rallied after six fruitless innings against Oswalt, pitching in St. Louis for the first time since the Astros' NL championship series clincher last fall. Jason Marquis worked seven strong innings for the NL Central leaders, who sent the Astros to their sixth loss in seven games.

"I got another chance, and I came through," Pujols said. "That's what it's all about, stay focused and get a good pitch to hit, and hopefully come through."

Aaron Miles singled off Trever Miller (0-1) to start the seventh and John Rodriguez coaxed a full-count walk with two outs ahead of Pujols, who hit his major league-leading 25th homer off Chad Qualls on a 2-0 pitch.

Pujols also leads the majors with 64 RBIs. He's the third-fastest to 25 homers, reaching it in 51 games while Barry Bonds required 47 in 2001 and Mark McGwire needed 50 in 1998. He's on pace for 79 homers and 203 RBIs.

"I don't concentrate on those numbers, I concentrate on making my plays and concentrate on coming through and winning some games," Pujols said. "If you concentrate on RBIs, home runs, batting average, anything like that, you're going to lose the focus you have."

Astros left fielder Chris Burke didn't think the ball was gone at first, camping under a spot well in front of the warning track for a few seconds before retreating to the wall. Neither did manager Phil Garner.

"I didn't think it was hit good at all," Garner said. "He's the hottest man on the planet with somebody in scoring position.

"At first it looked like it wasn't going to go out and then I think the god of baseball grabbed it and pushed it out."

Marquis (7-4) has won his last four starts and is 5-1 against the Astros the last two seasons. He worked around early control problems that led to hit batters on consecutive pitches and to the Astros' lone run on Preston Wilson's infield hit in third. He struck out two, walked two and allowed only three hits.

Oswalt, who's 0-2 in his last five starts, left with a 1-0 lead with tightness in his right hamstring after holding the Cardinals to seven hits and a walk. He struck out five and stranded two runners in the first, fourth and fifth.

Oswalt said he hurt his hamstring on his first at-bat, a groundout in the third.

"It didn't really pull, it just kind of balled up on me and it tightened up pretty bad," Oswalt said. "Every inning after that it kind of got worse and worse.

"I could have pushed it one more inning but it was probably better to come out now than miss three or four starts."

Last year, Oswalt was 2-0 with a 1.29 ERA in two NLCS starts against the Cardinals, and he silenced them in Game 6 after Pujols' dramatic homer off Brad Lidge won Game 5.

Craig Biggio became the 23rd player to reach 10,000 at-bats when he grounded out to end the seventh. Biggio also was one of three players hit by pitches from Marquis, extending his modern-day record in that category to 277.

Marquis hit Willy Taveras on a 3-1 pitch, then plunked Biggio on the next pitch with one out in the third. Morgan Ensberg walked with two outs and Taveras scored on Wilson's sharp grounder to third that handcuffed Scott Rolen.

Isringhausen, the Cardinals' third pitcher, worked the ninth for his 17th save in 19 chances and 11th in a row.

Notes: A sellout crowd of 45,509 was the largest at new Busch Stadium, boosted when about 5,000 seats in left field were used for the first time. That portion overlapped the old Busch, demolished last winter. ... Lance Berkman got his 1,000th career hit on a sharp single off the right-field wall in the fifth. Berkman, hampered by a hyperextended right knee, started for the first time in three games. ... The Astros are 8-17 on the road. They're 10-18 in May after a 16-8 April. ... Jim Edmonds missed his third straight game with a lower abdomen injury. He said he would undergo tests for a possible sports hernia on Tuesday. ... David Eckstein was 3-for-5 for his 22nd multihit game of the season. He entered the game tied for the NL lead with Miguel Cabrera of Florida.