updated 11:49 p.m. ET Aug. 21, 2008

CHICAGO - J.T. O’Sullivan made a perfect case to start. And Alex Smith’s counter-argument didn’t measure up.

Even so, 49ers coach Mike Nolan wasn’t ready to announce a starting quarterback.

O’Sullivan threw for 126 yards and a touchdown in his limited time while Smith struggled, and the San Francisco 49ers beat the Chicago Bears 37-30 on Thursday night.

Although the third preseason game usually is a dress rehearsal for the opener, Nolan wouldn’t declare a winner in the quarterback race.

“We will talk about it more (Friday),” Nolan said. “I would like to watch the film, talk to our players, before any announcement or anything like that is made. But I did like what I saw in all three of them.”

After two mediocre outings against Oakland and Green Bay, O’Sullivan couldn’t have performed any better against the Bears.

He was 7-for-8 with a perfect 158.3 passer rating in his third preseason start. He led the 49ers (2-1 preseason) to field goals on the first two possessions and a two-play, 77-yard touchdown drive on the third one. He hit Vernon Davis with a 40-yard pass and then scrambled to his right before throwing a 37-yard touchdown pass to Jason Hill to give the Niners a 13-10 lead less than a minute into the second quarter.

“That was a great play call,” he said. “Jason did a great job of running so fast across the field and just made a great play on the ball.”

And O’Sullivan did a good job, too. The question is whether he did enough to beat Smith, who came on early in the second quarter and was 6-for-17 with 83 yards and a touchdown, even though Nolan wasn’t about to make an announcement. He even left the door open for Shaun Hill, who played well late in the game.

He entered the game after Chicago’s Garrett Wolfe fumbled the kickoff following Hill’s touchdown pass, giving the Niners possession on the Bears’ 16. Moran Norris ran it in from the 1 to make it 20-10.

Smith also led the Niners on a 62-yard drive that ended with a 12-yard touchdown pass to Dominique Zeigler, giving the 49ers a 27-20 lead with 9:28 left in the third quarter. Otherwise, it was a rough night for him.

Hill replaced him late in the third quarter and was 6-for-7 with 60 yards against the Bears’ reserves. But after Thursday’s game, the starting job appears to be O’Sullivan’s even though there was no announcement.

“Everybody wants to know who the starting quarterback will be,” Davis said. “I don’t know. I have no idea. Everybody looks good to me.”

The Bears’ quarterback drama ended Monday when coach Lovie Smith selected Kyle Orton the starter over Rex Grossman. And Orton backed it up with a strong showing.

He was 10-for-17 with 147 yards, two touchdowns and no interceptions for Chicago (0-3). He had four passes of 18 yards or more, including a 55-yarder to Mark Bradley — a big improvement over the first two preseason games, when his longest completion was 17 yards.

“I thought I played well and I thought we played well as a unit,” said Orton, who started 15 games as a rookie in 2005 and three last season. “I thought as a unit we had been playing all right, we just hadn’t been scoring points. Finally we kind of got over that and put up 20 points in the first half, which was good.”

MORE FROM NFL

NFL Section Front

Time running out for McNabb-Reid team PFT: Romo leaves Simpson 'heartbroken' with split   PFT: Ravens' Mason retires PFT: Griese canned by Bucs, becomes free agent PFT: 'Next question!' T.O. a Bill more than 1 year? PFT: NFL to produce reality show ... in China PFT: Bon Jovi refused to join Estefan, Buffett in Miami McNair called 'hero, legend, warrior' at funeral PFT: Ray Lewis tells sons to be proud of McNair PFT: Will UFC be bigger than NFL? Please NFL Section Front   Add NFL headlines to your news reader: