ST. LOUIS (AP) -- Chris Carpenter coasted into the playoffs last season. This year, he's been dominant down the stretch.
Carpenter has two complete games in his last three starts in a big switch from last season, when he staggered into October with a 9.14 ERA over his final four regular-season starts. The Cardinals clinched the NL Central last year on Sept. 15, which had a lot to do with Carpenter's late slide -- and he won the Cy Young Award with a 21-5 record.
"I learned from last year that no matter what the situation was, not to give them away," Carpenter said. "I'm trying as hard as I can to stay locked in and mentally focused on what I need to do."
Juan Encarnacion had two RBI for the Cardinals, who dominated in the first of seven meetings with the Astros over the final 20 games. St. Louis ended a three-game skid and leads the NL Central by five games over Cincinnati and six over the Astros, who beat them in the NLCS last year to go to the World Series.
"I think it's important to note," manager Tony La Russa said. "You just can't make too much of it. Enjoy it for a while."
Taylor Buchholz was recalled from Triple-A Round Rock to sub for Andy Pettitte, who was pushed back a day because of a heavy workload and a minor ankle sprain. Buchholz (6-10) made his first appearance for Houston since July 27 and allowed five runs in 3 1/3 innings.
"I thought I'd figured some of this stuff out down in Triple-A and I just went back to doing the same old thing I was doing in the past," Buchholz said.
Carpenter (14-6) is 4-0 with a 2.27 ERA in his last seven starts. He lowered his NL-leading ERA to 2.84 with his fourth compete game of the season and third shutout, which tied Arizona's Brandon Webb for the major-league lead.
"That's kind of the way he's been pitching," La Russa said. "He's such a horse."
Carpenter struck out six and walked two, raising his career record against Houston to 5-2 with a 2.52 ERA. He has 24 career complete games and 12 shutouts.
He had been 0-1 against the Astros this season while allowing nine runs in 14 innings. The Astros were shut out for the second straight game, and 13th time overall, after Adam Wainwright worked the ninth.
Carpenter has worked eight or more innings in five of his last six starts. He's 7-3 with a league-leading 1.47 ERA in 15 starts at home.
Belliard had been in an 0-for-20 slump before his RBI single off Buchholz in the third. His three-run triple off Fernando Nieve capped a five-run inning that put the Cardinals ahead 7-0.
"I had a rough week," Belliard said. "I didn't know I was 0-for-20, but I knew I was 0-for-the-last-six-games."
Encarnacion had an RBI single in the third and drew a bases-loaded walk from Nieve in the fourth.
Astros shortstop Adam Everett committed two errors, one of them contributing to five unearned runs in the fourth. He lost his grip and double-pumped while preparing to throw on a grounder by Aaron Miles, and Miles ended up beating the throw with one out and nobody on.
Five of the next six batters reached safely.
"I just never got a handle on it," Everett said. "When you've got a guy like Carpenter on the mound, two runs, you've got a chance. But seven runs by the fourth inning, that's tough to overcome."
Everett, who also misplayed a short hop on Carpenter's liner up the middle in the second, has only seven errors. This was his fifth two-error game and first since May 1, 2005.
Carpenter has 35 victories the last two seasons, tied for most in the majors with the White Sox's Jon Garland. Carpenter also has only five walks in 61 1/3 innings over his last eight starts. ... Buchholz's outing ended a run of 12 straight games in which Astros starters allowed three runs or fewer and one or fewer in eight of those games. ... The last Cardinals pitcher to lead the league in ERA was Joe Magrane at 2.18 in 1988.