SANTA CLARA, Calif. — J.T. O'Sullivan will start at quarterback for the San Francisco 49ers when the NFL regular season begins next month.

O'Sullivan clinched the job with a strong performance during Thursday night's 37-30 exhibition victory over Chicago, and 49ers coach Mike Nolan said it was time to make O'Sullivan's status official after a summer of uncertainty.

"J.T. O'Sullivan will be our starting quarterback going into the season and I'm expecting him to succeed," Nolan said Friday. "I'm very confident J.T. is at the point where he's our best man for the job right now."

O'Sullivan, a long shot to become the starter when training camp began at the end of July, overtook veteran holdovers Alex Smith and Shaun Hill during the past two weeks. The sixth-year player, now with his eighth NFL team, has never started a regular-season game in the league.

O'Sullivan was picked to start San Francisco's preseason opener Aug. 8 against Oakland and has been practicing and playing with the first unit since.

Smith and Hill struggled to grasp new offensive coordinator Mike Martz's complex system, opening the door for O'Sullivan.