"I'm a UPS driver," Hill said. "Every time, that's what I say. I can still pull it off."

After six years with two teams and countless practices as a lowly scout team quarterback, Hill no longer must pretend to drive a brown truck. He'll never again have to explain why his entire career consists of two kneeldowns for the Minnesota Vikings.

He's in charge of the San Francisco 49ers' offense for at least one week, and probably for the rest of the season.

After passing for 181 yards in his first significant NFL playing time last Sunday, Hill will make his first start Saturday night against the Cincinnati Bengals. Alex Smith is done for the season following shoulder surgery, and Trent Dilfer likely is finished as well after incurring a concussion last week.

Hill can't think of another player who stuck in the league for six years with no real playing time. He's been a No. 3 emergency quarterback for most of that time, save nine weeks as Brad Johnson's backup with the Vikings in 2005.

"The two kneeldowns (to end that season) were perfect plays, so I had a good start," Hill said with a grin. "I would have thought I would play before my sixth year, but this is the way it played out, and I'm very excited for this opportunity. ... My goal has never been to be a third-string quarterback, so obviously this is an opportunity to use this as a stepping stone."

The 49ers are cautiously optimistic about Hill — and since they've already got the league's worst offense and the least successful passing game, how much worse could he be?

Hill was downright impressive at times while filling in for Dilfer last week, going 22-for-27 and throwing a touchdown pass to Arnaz Battle. Hill also committed two turnovers, partly because he has trouble gripping the ball at times with a protective wrap on the injured index finger of his throwing hand.

"I like Shaun. The communication is good," said tight end Vernon Davis, who caught five passes for 42 yards from Hill in the second half last week. "In practice, I'm everywhere he wants me to be. He's going to get through his reads, and he's going to give you a shot. If you're open, he's going to pop you right away, and I tend to get open."

The 49ers' inability to get the ball to Davis has been one of the offense's most perplexing faults this season. Hill showed none of Smith's shyness in finding Davis or backup tight end Delanie Walker, who caught six passes for 65 yards from Hill against the Vikings.

"If they come to me, the next couple of plays opens everything up, because then they have to pay attention to me," Davis said.

Hill seems to agree, perhaps because of all the time he's had to analyze the 49ers' offense over the past two years. Hill's quick release impresses coach Mike Nolan, as does the quarterback's perseverance.

"He's had a good week of practice, and he's an instinctive player," Nolan said. "He knows the offense. He's been waiting six years for his shot, so I'm excited for him."

Hill spent two years in junior college in his native Kansas before playing two seasons at Maryland, which reached the Orange Bowl in 2001. The undrafted free agent stuck for four seasons with the Vikings, then won the No. 3 job in San Francisco last season.

Between seasons in Minnesota, Hill got his last starting assignment for the Amsterdam Admirals in NFL Europe in 2003. He has found a groove as the 49ers' scout team quarterback and an occasional receiver, showing surprisingly good hands.

But at 27, he's ready to find out whether he's more than a good practice player.

"Now, you have to come out to practice and be as mentally focused as you would be in a game," Hill said. "When you're running the scout team, to be honest, some days you can get away with not being as focused. ... You go out there with the scout team, you can just grip it and rip it. You throw an interception, great job, defense. It's not the quarterback's fault."

DILFER'S HEAD: Trent Dilfer briefly lost consciousness on the

hard hit that knocked him out of last week's game, but the veteran quarterback still isn't ready to give up on the season.

Dilfer incurred the third major concussion of his career last Sunday while attempting to scramble for a first down in the 49ers' 27-7 loss to Minnesota. Dilfer also had concussions in 1995 and 2001, yet the 14-year veteran believes the league's increased awareness of head safety could allow him to return.

"Five years ago, I would have practiced Wednesday (after a concussion)," Dilfer said. "You just didn't know any better. The teams are doing a better job protecting their investments, which are the players."

It wasn't that way 12 years ago when Dilfer got his first concussion. He kept playing after being hurt until his teammates pulled him out.

"I guess the tight end was calling plays for me in the huddle," said Dilfer, who doesn't remember the event.

EXTRA POINTS: QB Alex Smith's surgery on his separated right