SANTA CLARA, Calif. -- J.T. O'Sullivan took another step closer to becoming the San Francisco 49ers starting quarterback.

O'Sullivan was selected by coach Mike Nolan on Thursday to start San Francisco's exhibition home opener against the Green Bay Packers on Saturday. O'Sullivan also started the preseason opener last week at Oakland.

Nolan continues to assert there is a three-way competition between O'Sullivan and holdovers Alex Smith and Shaun Hill to become the starter for the team's regular-season opener Sept. 7 against Arizona.

But O'Sullivan clearly has taken the lead in that competition. He has taken all the snaps with San Francisco's first-unit offense in team drills during training camp practices this week and will start against a team he spent time with in 2004.

"It's another opportunity to showcase what he can do, as it is for everyone else," Nolan said. "Right now, we are just in an evaluation process."

O'Sullivan, a sixth-year journeyman with his eighth NFL team, moved the San Francisco offense while completing 5 of 8 passes for 71 yards in one quarter of action last week against the Raiders.

But he also threw an interception near Oakland's goal line to end one drive and lost a fumble near midfield to end another.

Nolan said O'Sullivan will play most of the first half along with the rest of San Francisco's regulars against the Packers. Smith and Hill will come in after that in the same rotation the 49ers used during last week's 18-6 loss at Oakland.

"I feel I'm kind of evolving every day and going out there and trying to play exactly how they want me to play," O'Sullivan said. "The next step is to be able to do it consistently. This game is the next opportunity to show what I have."

O'Sullivan did not take any snaps in 11-on-11 team drills during the first seven days of training camp as Smith and Hill got all the work. But both players have come along slowly this summer in new coordinator Mike Martz's complex offensive system.

O'Sullivan worked in that system last year when both he and Martz were with the Detroit Lions. O'Sullivan played in four games with the Lions last season and threw the first regular-season passes of his NFL career.

Nolan had said throughout the first week of camp in July that he planned to evenly divide practice time and playing time during the preseason between his quarterbacks. He still has not put a timetable on when he plans to determine his starter for the regular season.

"Obviously, were talking about what gives us the best opportunity to win," Nolan said. "I am still encouraged by all three quarterbacks and feel a lot better than I ever have (about the position) since I've been here at any time."

Smith, who worked with the second team in Thursday's practice, will not be with the team Friday during its final preparation for Saturday's game.

Smith was scheduled to fly to San Diego late Thursday to attend Friday services for David Edwards, Smith's former roommate and close friend since childhood. Edwards committed suicide Sunday at age 24

Smith has been excused from Friday's team activities to attend the service, which will be held at Smith's parents home in San Diego. Edwards and his family also were very close with Smith's family.

"Obviously, this has been a really hard week, let alone the quarterback stuff going on," Smith said. "With this going on, it kind of puts things in perspective for me. It will be good to go down there and see all the people, all the friends, to kind of deal with it."

Smith will fly back to the San Francisco Bay Area on Saturday morning and be ready for his opportunity against the Packers that evening.

"I'll come back and treat it the way I always have, just focus in and take advantage of the reps I get and try to make the most out of them," Smith said.

Copyright 2008 by The Associated Press