St. Louis ? In Roger Clemens and Roy Oswalt, the Houston Astros have one of the best pitching tandems in all of baseball.

Only one problem going into the NL championship series: With no time to rest, those guys have been aced out of starting the first two games against the St. Louis Cardinals.

Instead, Houston hopes Brandon Backe can shut down the likes of Albert Pujols, Scott Rolen and Jim Edmonds in the opener tonight at Busch Stadium. Then, Pete Munro gets the ball for Game 2.

Backe, a converted outfielder from the Tampa Bay system, and Munro, cut by Minnesota in June, began the season in the minors. Together, they combined for nine wins in the majors.

“We don’t feel handicapped in any way whatsoever,” Astros manager Phil Garner said Tuesday. “This is what it took for us to get here. This is what we’ll go with.”

Garner leaned on his two aces to get the Astros through the first round of the playoffs. Both pitched on three days’ rest, with Oswalt winning the decisive Game 5 on Monday night in Atlanta.

Clemens and Oswalt each went 2-0 against the Cardinals this year. Now, they’re pushed back to pitching over the weekend in Houston — not that St. Louis manager Tony La Russa is relaxing.

“We’re not going to fall into the trap tomorrow, because Clemens or Oswalt is not pitching, that we’ve got some big advantage,” he said. “They’ll have a legitimate starting pitcher, a legitimate bullpen, a legitimate club behind them.”

Still, St. Louis slugger Larry Walker was a little curious, especially about Munro. With batting practice wiped out by rain, the Cardinals were talking, and were certain Munro was starting the opener.

“I just know he’s pitching the first game,” Walker said. “I don’t even know if I ever have faced him, really.”

Walker had, going 1-for-3 with a double.

Coming off the first playoff series victory in their 43-season history, the wild-card Astros take on the team that led the majors with 105 victories. Backe will start on three days’ rest for the first time in his career, opposed by Woody Williams, who grew up in Houston.

“I’ve always been an Astro fan. It’s a team I always rooted for my whole life,” Williams said. “Now I have an opportunity to be the one that sends them home on a sour note. It’s kind of bittersweet for me.”

For his family, too.

“I have left tickets for one of my family member’s brother before. He’s sitting there cheering for the Astros,” he said. “So next time, I put him way up at the top. That was when I was pitching.”

Chances are the matchup between NL Central opponents will not generate the kind of heat the Red Sox-Yankees rivalry produces in the ALCS. Even though Backe contends “we’ve had some words exchanged every now and then,” these clubs keep it pretty civil.

“Ever since I’ve been in the league, we really had terrific competitions,” La Russa said. “I think we’re two hot clubs, two confident clubs.”

The one squabble they had came early in April 2002, when the Astros arrived at Busch Stadium and saw a sign that proclaimed the Cardinals co-champions of the Central Division.

Both teams went 93-69 the previous year, but Houston won the season series 9-8 and the Cardinals were the wild-card team in the playoffs. The Astros finished 10-8 against the Cardinals this season, with Houston sweeping a three-game series at home in late September.

Backe recorded one of those key wins, part of a 5-3 season when he didn’t reach the rotation until August. Backe won Game 3 against the Braves, throwing six effective innings. Munro finished 4-7 and has not pitched since Oct. 1.

“I think the adrenaline’s going to take away any soreness or whatever I have,” Backe said

Then again, pitchers with less experience have occasionally excelled at this time of the year.

The fewest regular-season wins by a Game 1 starter in any postseason series is three, by Seattle’s Bob Wolcott in the 1995 ALCS.