It's not as if the Houston Astros conceded Games 1 and 2 of the National League Championship Series to the St. Louis Cardinals before the fact. But there was a sacrificial element to their decision, one they had almost no choice but to make, to send a pair of defenseless pitchers with 19 combined career victories to the mound against the fiercest offense in baseball, which predictably ate them up.

The reason the Astros could do such a thing and still live with themselves was because they knew what they held in reserve for Games 3 and 4 this weekend at Houston's Minute Maid Park -- Roger Clemens on Saturday, Roy Oswalt on Sunday. Two Cy Young contenders. One hundred thirty-one wins between them in the past four years alone. A 4-0 combined record against the Cardinals this season.

"I've been in this position before . . . where you're backed into the corner," said Clemens, who is 9-6 in his career in the postseason. "But it's nice to be back at home."

For the Astros, then, the real NLCS -- the one they actually have a chance to win -- starts now. Their decision to throw Brandon Backe and Pete Munro to the wolves in Games 1 and 2 was costly, as it left them in a 2-0 hole to the Cardinals entering Saturday's Game 3, with very little margin for error on the parts of Clemens, who faces St. Louis's Jeff Suppan on Saturday, and Oswalt.

"If you've got to be 0-2, obviously coming back with your number one and number two starters is the way to get back in it," Astros Manager Phil Garner said. "We've counted on them all year, and we're going to count on them right now. They're our two horses."

Starting pitching was the one clear advantage the Astros held in this series -- for the simple reason that Clemens and Oswalt were significantly more dominant this season than any two arms the Cardinals could send to the mound. However, that advantage was lessened considerably by the fact the Astros used Clemens and Oswalt in Games 4 and 5 of the Division Series win over Atlanta, making them unavailable for the first two games of the NLCS.

Needing to win only one of the final two games against Atlanta, Garner could have saved Clemens for Game 5 on full rest, then brought back Oswalt for Game 1 of the NLCS. Instead, Garner used Clemens in Game 4, which the Astros' bullpen lost, and Oswalt in Game 5. Both pitchers were starting on short rest, and neither lasted more than five innings.

The Astros are in desperate need of some innings from their workhorses, as they have not gotten as much as six innings out of a starter since Backe went six against the Braves in Game 3 of the Division Series.

"Every time we get those guys [Clemens and Oswalt] out there, obviously it's a better opportunity for us," said Astros first baseman Jeff Bagwell. "We're better off. That's not a knock on anybody. It's just a fact."

In two games in St. Louis, the Astros saw their starters leave early and their bullpen get pummeled by the Cardinals' relentless offense, which is averaging 6.3 runs per game in the postseason. Four times in the first two games, the Astros brought a reliever into a tight situation and watched him give up either the tying or go-ahead run to the first or second batter he faced.

The perception that the Astros have no trustworthy relievers beyond closer Brad Lidge has been reinforced in the first two games, as the bullpen has pitched to a combined ERA of 10.56, while Lidge -- who was standing on the bullpen mound, fully warmed up and ready to come in, when Dan Miceli lost Game 2 in the eighth inning -- has yet to see action.

The Astros' return to Minute Maid Park with their aces on the mound has made them more confident than might be expected of a team facing a 2-0 series deficit. The Astros won their final 18 home games of the regular season -- part of a remarkable 36-10 closing kick that earned them the NL wild card -- and stretched the streak to 19 games in Game 3 of the Division Series before being beaten by the Braves in Game 4. Clemens and Oswalt combined to go 23-7 at home.

"I don't think we feel intimidated or down whatsoever," third baseman Morgan Ensberg said. "I just think we're in a bad spot. Of course, we've been playing for four months in a bad spot, so we're in a very familiar area."

Should the Astros fail to survive the weekend, there remains a chance Saturday's start could be the last of Clemens's storied 20-year career. If so, it would be his second "final" start, following the one in last year's World Series, when Clemens, having already announced his retirement from the New York Yankees, bade a touching farewell to baseball at Miami's Pro Player Stadium during Game 3 against the Florida Marlins.

Of course, Clemens unretired to join his hometown team this winter and wound up winning 18 games. He has not addressed speculation about his future, but Astros insiders expect him to play again next season.

"I catch myself every once in a while thinking about it, that this could be it," Clemens said. "But when you're in situations that I've been in over the last few months, it's hard to sit there and ponder those thoughts. . . . I have a lot on my plate, like I have [all] year, like I will this offseason. I won't look too far ahead just yet."

On the other hand, should the Astros survive the weekend, send the series back to St. Louis and prevail over the Cardinals, Clemens would be matched up at least once against one of his former teams -- the Yankees or Boston Red Sox.

To get to that point, however, the Astros need Clemens to win on Saturday. They need Oswalt to win on Sunday. In that case, Garner will be faced with another critical decision -- whether to bring back Clemens and Oswalt again on short rest in Games 6 and 7. Garner has refused to address such speculation thus far.

But given what tends to happen to the Astros without one of their two aces on the mound, there seems to be little choice.

Roger Clemens, top, and Roy Oswalt are being counted on to salvage Games 3 and 4 for the Astros, with the prospect again that tonight's game could be Clemens's last.