ST. LOUIS -- This might have been Mark Mulder's first taste of this particular level of October baseball, but it's not like you have to explain anything about the postseason experience to him.

Whether you're pitching in the Division Series like he had for his previous five postseason starts, or you're in the National League Championship Series like he was in his Game 2 start Thursday night, Mulder knows the margin for error is slight this time of year.

And when you're up against the likes of the Astros' Roy Oswalt when he's on top of his game, it's even slighter.

As in, nil.

That was certainly evident Thursday night, when Mulder recovered from some early location issues to pitch seven strong innings, only to walk away the losing pitcher in the Astros' 4-1 victory at Busch Stadium that sends the series back to Houston tied at a game apiece.

"This is playoff baseball, man," Mulder said. "There's a reason I'm 3-3 in the playoffs. Runs come at a minimum in these games, and that's because you pretty much always have good pitching staffs going against each other now."

Everybody knew that was the case going into this series -- pitching was a big reason each of these teams reached this level. Everybody knew Oswalt could deliver a performance for the Astros that could handcuff even the productive lineup like the Cardinals, too -- and that's what he did, other than one monster shot for a solo homer by Albert Pujols.

Mulder was up to the challenge, too. But, like the man said, it doesn't take much to hand you a .500 record despite a 1.91 ERA in six postseason starts.

In his sixth start, Mulder had a couple of pitches get away from him, and that was just enough to give Oswalt and the Astros the edge they needed to take a big swing game in this series.

You can't put the loss on Mulder's shoulders, that's for sure. His overall performance pretty much matched what co-ace Chris Carpenter did the night before in Game 1. Mulder gave up two runs (one earned) on eight hits while striking out six, and Carpenter allowed two earned runs on five hits while striking out three in the opener.

But the runs Mulder allowed came earlier in the game, and they wound up being enough to be costly against Oswalt, who delivered eight innings of one-run ball. A triple by Chris Burke and a passed ball to score him in the second inning put the Cardinals behind in a game for the first time this postseason. Then came a double by Brad Ausmus in the fifth that led to another run, pushing the deficit to two.

"That triple and that double were just sinkers that stayed up," Mulder said. "If I make better pitches with those, it's a different story."

That Mulder was pitching in an LCS game at all was a story in itself.

After all, he couldn't get there with the A's, who lost in Game 5 of the Division Series in 2001 and '02 with Mulder making two starts in each, and he was out of the 2003 series with a leg injury. Last year, the A's didn't make the playoffs for the first time in five years, and Mulder landed in St. Louis in a winter trade.

His first time in the LCS was pretty much same old, same old.

"It's really no different than any other playoff game," Mulder said. "I mean, it was a great atmosphere, and the fans were into it. It was fun being out there."

Just being out there at all was a good thing for Mulder, who was drilled in the pitching arm by a Joe Randa line drive in Game 2 of the Cardinals' three-game sweep of the Padres in the Division Series.

"My arm was fine -- no soreness, no nothing," Mulder said.

Just a bad case of Roy Oswalt. That's all that bothered Mulder and the Cardinals in this one.

As he dissected his performance afterward, Mulder could count on one hand the number of pitches he really would have liked to have had back -- just those couple of sinkers and a cut fastball he didn't get in on Craig Biggio quite enough. Other than that, not a lot of nits to pick.

But he knows that's all you need, a pitch here and a pitch there.

"Little things can turn into big things when you're in the playoffs," he said.

A guy with a .500 record and a 1.91 ERA in the postseason knows that as well as anyone.