With their starter sidelined by a fractured rib, the Tampa Bay Buccaneers will turn to the second half of their Johnson & Johnson quarterback tandem for Sunday's game against the spiraling Carolina Panthers.

Backup quarterback Rob Johnson took all the snaps with the No. 1 offense on Wednesday, is scheduled to do so again in Thursday's practice, and will replace the injured Brad Johnson in the lineup. It will mark the first start for Rob Johnson since the middle of the 2001 season, when he was playing for the Buffalo Bills, and offers yet the latest opportunity for the eight-year pro to rehabilitate a once-promising career.

Brad Johnson could miss another week with the injury, which has caused him pain and discomfort, and precluded him from being able to move freely on the field.

Although the more mobile Rob Johnson will add the movement dimension that coach Jon Gruden prefers in his starting quarterback, he must prove that he can make sound judgements and avoid turnovers. Gruden is a big fan of Rob Johnson, clearly believes his career can be salvaged in the Bucs system, and is confident the quarterback will be successful against the Panthers.

"He's been right on the screws in terms of what we need from him mentally so far," Gruden said. "He's got a much better understanding of what we want done, so it's really just a matter of us playing better around him."

Rob Johnson officially becomes the 49th different starter leaguewide in 2002, a season in which the quarterback carousel is spinning wildly.

The former Southern California standout will be making his 28th career start. He has appeared in three games this year, including replacing Brad Johnson in the second half last week, and hit four of seven passes for 31 yards. For his career, Rob Johnson has completed 430 of 705 passes for 5,197 yards, with 29 touchdown passes, 20 interceptions and an 85.5 passer rating.

While he is more careful with the ball than some people perceive, Johnson often holds the ball too long and takes too many sacks. That is hardly in keeping with the Tampa Bay offense, a design based on three- and five-step drops where the ball must be delivered quickly. That is even more key now, with the battered condition of the Bucs offensive line.

One more change on offense is expected to be at wide receiver, where Keenan McCardell is nursing a fractured scapula. While it is conceivable that McCardell can play in the game, he almost certainly will be replaced by Joe Jurevicius in the starting lineup.

Yet to be determined is whether right guard Cosey Coleman, charged earlier this week with misdemeanor battery against his girlfriend, will play Sunday. Gruden said he is still gathering information on the incident.

Len Pasquarelli is a senior writer for ESPN.com.