The 49ers have named J.T. O'Sullivan as their starting quarterback for the regular-season opener, coach Mike Nolan told reporters Friday.
The long-anticipated announcement comes as no surprise after O'Sullivan's impressive performance Thursday night against the Chicago Bears in the 49ers' third exhibition game. O'Sullivan had been working with the first-team offense since Aug. 6, moving past former starter and 2005 No. 1 overall draft choice Alex Smith on the depth chart.
"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, 29, has never started a regular-season NFL game. Smith, 24, was the starter until a shoulder injury limited him to seven games in 2007.
The 49ers signed O'Sullivan in March after naming Mike Martz as their offensive coordinator. Martz and O'Sullivan were together with the Detroit Lions last season. O'Sullivan's familiarity with Martz's offense gave him an edge in a competition that began with Smith and veteran Shaun Hill as the primary competitors.
"This hasn't been a case of Alex and Shaun not performing well," Nolan said. "This has been a case of J.T. performing very well. That's why we are where we are. J.T. has very good command of the offense, he's played well in all three preseason games, and now it's time for us to get ready for the regular season."
O'Sullivan has completed 60.6 percent of his passes for 351 yards, two touchdowns and two interceptions in three exhibition starts this summer. His passer rating is 91.8. Smith, working mostly with the second-team offense, has completed 42.1 percent of his passes with one touchdown, no interceptions and a 67.4 rating.
"We want to play our best players that give us the best chance to win," Nolan said. "For our football team's sake, it's time to get ready for our opening game. This [decision] puts more focus on where it should be now."
Smith enters the season as the No. 2 quarterback, with Hill in the No. 3 role.
San Francisco opens the regular season Sept. 7 versus the Arizona Cardinals.
The Associated Press contributed to this report.