HOUSTON -- Roger Clemens hopped off the mound, pumped his right fist and muttered to himself all the way to the dugout. His work was done and the Houston Astros were exactly where they wanted to be -- right back in the NL championship series.

Pitching to save the Astros' season, Clemens came through. He slowed down St. Louis for seven innings, closer Brad Lidge finished off the Cardinals and Houston went on to win 5-2 Saturday, cutting its deficit to 2-1.

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"It was a must-win for us," Clemens said.

Jeff Kent's two-run homer capped a three-run burst in the first inning. Carlos Beltran homered yet again, connecting along with Lance Berkman in the eighth to further highlight a series featuring sluggers.

Clemens made the early lead stand up, overcoming home runs by Larry Walker and Jim Edmonds and lasting long enough so that Houston manager Phil Garner could avoid using his beleaguered bullpen.

"What you saw today was exactly what he's done for us so many times," Garner said. "He finds a way to get it done."

No team in baseball's postseason has ever rallied from a 3-0 hole. The Astros won't have to try, either, and now start 20-game winner Roy Oswalt against Jason Marquis on Sunday in hopes of evening the best-of-seven matchup.

Clemens completed his outing by striking out pinch-hitter Roger Cedeno, then stalked and snarled his way back to the bench. Clemens' wife, Debbie, celebrated by double high-fiving a friend in the stands and the fans roared right along.

"No matter my age or what I've done in the past, you want to make a good showing," he said.

With the crowd raising a ruckus, Lidge relieved Clemens and blew away the Cardinals, striking out Walker and Game 2 star Scott Rolen.

Beltran added insurance when he homered in his fourth straight postseason game, tying the record set by Jeffrey Leonard in the 1987 NLCS. The solo shot was Beltran's seventh homer in the playoffs, and combined with Berkman's drive gave Lidge extra room to work.

"This is what we were expecting," Beltran said.

Making his first appearance in a week, Lidge walked a batter and hit one in the ninth before striking out pinch-hitter John Mabry to end it.

"It felt great. And I'm definitely available for tomorrow," Lidge said.

The Astros won for the 20th time in their last 21 games at Minute Maid Park, and assured themselves of playing at least twice more at home.

"The atmosphere is electric here right now," Lidge said. "We've been playing with a lot of confidence here."

Houston also continued to lead in the home-run derby, hitting nine in two games to St. Louis' seven.

"Dangerous lineups and mistakes, guys are punishing," Cardinals manager Tony La Russa said. "They're not popping any of them up."

Jeff Suppan did fine as the Cardinals' starter, but the result was the same. He was 1-4 against the Astros this season, including 0-3 in head-to-head duels with Clemens.

At 42, Clemens became the oldest starting pitcher to win a postseason game - he bettered the mark he set earlier this month when he beat Atlanta in the first round.

There is a chance that this might have been Clemens' final game, especially if the Cardinals win the next two and he decides to retire -- for real, this time.

On Friday, however, Clemens said it was way too early to think about that. He's got his eyes on a bigger prize: pitching his hometown team to its first trip to the World Series.

Clemens gave up four hits, struck out seven and walked two. He admitted a day earlier that he probably would be "anxious" about this assignment, and clearly was not at his overpowering best -- at least not at the start.

He didn't challenge hitters in the early innings and certainly didn't threaten them with anything up-and-in. Despite several chances, he didn't put away any batters with two strikes until fanning Edgar Renteria in the fourth.

Next up was Reggie Sanders, and a curious sequence followed. With the count 2-2, two outs and a runner on second base, Clemens didn't see Sanders ask for time and step out of the batter's box.

As Clemens came forward, he suddenly saw the situation and soft-tossed the ball toward the Cardinals' on-deck circle to the left of home plate, where Mike Matheny caught it on a bounce.

Clemens pointed in, as if to ask who had called time, and catcher Brad Ausmus trotted to the mound.

"Not a big deal," Clemens said.

Whether it ruffled him or not, Clemens quickly got into a rhythm, recording four of his next six outs on strikeouts.

Suppan was equal to the task in the middle innings, retiring 10 straight before leaving for a pinch-hitter in the seventh.

Back at the ballpark where they had won 19 of their last 20, the Astros came out full of optimism. During the pregame introductions, Brandon Backe was even announced as the guy who "will be pitching Monday."

Those giddy feelings lasted all of six pitches. That's when Walker neatly went the opposite way -- as he did over and over in batting practice -- and lined a drive to left-center for his fourth homer of the postseason.

Edmonds opened the third with a drive into the Houston bullpen in right, closing the Cardinals to 3-2.

Astros Prepare To Sell World Series Tickets

If all goes as planned, the Astros plan to start selling tickets to the World Series Monday.

The first step to purchasing the tickets began Thursday at 9 a.m. Fans must register at www.astros.com before Friday at 5 p.m.

On Saturday, a random drawing will be held. Those fans selected will be allowed to buy World Series tickets on Monday. If the Astros make it to the World Series, the tickets will be for games held at Minute Maid Park.