HOUSTON -- Although Roger Clemens won the National League Cy Young Award last year, within the walls of the Houston Astros clubhouse, Roy Oswalt is considered the ace of this staff. The 20-game winner was rewarded for his 2004 accomplishments with the 2005 Opening Day nod, which manager Phil Garner announced halfway through Spring Training.

Oswalt will start April 5 versus the St. Louis Cardinals, followed by Andy Pettitte on April 6 and Clemens on April 8. Brandon Backe, the No. 4 starter, will follow Clemens.

Garner had to make the tough decision between two deserving Opening Day candidates in Oswalt and Clemens, and this is one of the rare times that a Cy Young winner will not started Opening Day the following year.

"I have three No. 1 starters," Garner said, referring to Oswalt, Clemens and Pettitte. "Roy had a great year last year. Opening Day starter doesn't mean anything beyond that. When you have a clear choice to make like that, then you can go with guys you want to reward. But in this case, I think we have three guys you feel comfortable with. You can justify it in any number of ways."

This will be Oswalt's third consecutive Opening Day start. Shane Reynolds holds the club record for the most Opening Day starts with five, from 1996-2000.

Oswalt is 1-0 in Opening Day starts. In 2003, Oswalt earned the win after holding the Rockies to two runs (one earned) on four hits over seven innings. Last year, he took a no-decision in a 5-4 loss to the Giants. The right-hander allowed four runs on nine hits over 7 1/3 frames.

Oswalt acknowledged that receiving the Opening Day start is an honor, but that it doesn't mean his turn in the rotation is any more important than the No. 5 starter. But he also likes the idea that the Opening Day starter carries a lot of responsibility throughout the season, as is the case with most staff aces.

"Everyone's depending on you, when your slot comes back around," Oswalt said. "Especially if we get into a streak when we're not winning, they want you to be the guy to turn it around. A lot of times, Opening Day starters get to winning right out of the chute, and the guys behind you kind of follow you."

Said Pettitte: "I thought he might win the Cy Young before the season even started. He's unbelievable. What great talent he is, and he's just going to continue to get better. He's a horse. It's great to have him leading us off."

Oswalt isn't one to get caught up with the pomp and circumstance of various honors, including Opening Day. But he will go as far as to admit he is confident with what he brings to the mound, and he embraces the idea that his team feels that it's going to win every time he pitches.

"You have to believe in yourself," he said. "If you don't believe in yourself, then who will? It's a different sense going in there and being arrogant, but you have to have a way about yourself when you're going to the mound, that you know you're going to win.

"If you don't bring that out to the mound with you, when you doubt yourself, everyone around you doubts you."

Asked if he found it humbling that he's the No. 1 starter, ahead of No. 3 Clemens, Oswalt shook his head.

"I don't see it that way," he said. "I see it as, I pitch with him, I don't really see it that I'm pitching in front of him. That's what he believes, too. I know if he went first, he wouldn't believe that he went before us.

"It's an honor just to pitch with him. It doesn't matter if you go first or behind him. A lot of guys go through their career and never get to pitch with a Cy Young winner. Hopefully, we can pick up a few things from him and maybe become one one day, later on."