As Tampa Bay began defending its NFC South title a month ago, Sunday’s game in New Orleans was widely seen as one the Buccaneers were supposed to win.

Much has changed in a matter of weeks.

The surprising Saints (3-1) already have matched their win total for 2005. The Buccaneers (0-3) lost starting quarterback Chris Simms indefinitely after he ruptured his spleen in Week 3. They have yet to win. And with their season already in the balance, coach Jon Gruden decided to replace Simms with a rookie who’ll make his first NFL start before a hostile crowd in the rebuilt Louisiana Superdome.

The biggest challenge for Bruce Gradkowski?

“It’s not to throw up,” Gruden said, although the young quarterback isn’t so sure.

“Any time I throw up I feel like I’m going to have a good game, so I might have to,” Gradkowski said. “The nerves are going to be running a little bit, but that’s normal. … I’m just going to go out and have a good time. Just remember, this is football. This is what I’ve been doing since I was 8 years old.”

Beyond settling his stomach, Gradkowski needs to play to his strengths and avoid risks that could result in fumbles or interceptions, his coach said, noting that turnovers have led to nearly half the points scored against Tampa Bay this season.

“That’s the big thing, protect the football,” Gruden said. “And put your own spin on the position. It doesn’t have to be exactly like you’ve seen it on our (game film) in the last four or five years. You can put your own spin on it, and were hoping that’s an asset for us.”

Gradkowski ran the shotgun and demonstrated good scrambling ability in college at Toledo, making him stylistically different from Simms, who’s more of a drop-back, pocket passer like his father, former New York Giant Phil Simms.

Saints defenders are eager to test Gradkowski, but they’ve only seen a little film on him from the preseason. That is rarely a true indication of what a quarterback can do in the regular season, when game plans are more refined and tailored to the current week’s opponent.

“He’s playing in this league for a reason,” Saints interior defensive lineman Hollis Thomas said. “He can run and stuff if all else fails. I don’t know if he’s going to be flustered or whatnot. I’ll pin my ears back if I get a chance. But until then I’ve got to play within the defense and within the scheme.”

The rookie had the benefit of two weeks of preparation because Tampa Bay had its bye last weekend. And it would help him if the Bucs could run the ball as they were expected to do with Carnell “Cadillac” Williams leading the way.

However, Tampa Bay has a league-low 43.3 yards rushing per game and is last in the NFC in total offense (234 yards per game).