Coach Mike Nolan said Trent Dilfer will make his sixth start of the season Sunday against Minnesota in place of Smith, who was not made available for comment after his brief pre-practice workout.

The 49ers' medical staff will reassess the condition of Smith's throwing shoulder today and his regimen could gradually increase in the coming days, a team spokesman said. If Smith continues to have problems, season-ending surgery remains a possibility.

"It's going to be a touchy-feeling thing. We're just going to see how he does," Nolan said.

Nolan said he couldn't put a timetable on Smith's return. Because of the lingering nature of Smith's injuries, Nolan also remains wary of giving him the go-ahead even if he's eventually cleared by the team's medical staff.

"As we learned once before, that's not the total ticket," Nolan said. "You still have to ask the player, don't you? We'll re-evaluate at that time and see where we stand."

Smith suffered a third-degree right-shoulder separation Sept. 30 against Seattle when he was sacked and slammed to the ground by defensive tackle Rocky Bernard. He returned a month later but played ineffectively in three games.

Two days after his worst performance of the season, Nov. 12 at Seattle, Smith told reporters that his shoulder injury had never stopped bothering him and that it had been compounded by a forearm strain incurred during rehab. The remarks put Smith at odds with Nolan, who had insisted all along that his quarterback's sub-par performances were not related to his health issues.

During a news conference before practice, Nolan insisted he and Smith have patched things up and their communication has gotten better.

"I think our relationship is fine," Nolan said. "I think a lot more was made of that than had to be. We do communicate. Was there a little glitch at one point? Yes, but it was both sides. You've got to tell me if it's hurting. Don't surprise me with it. I can't read your mind. But outside of that, there's no issues there."

Nolan said there were no ulterior motives in his refusal to endorse Smith as the team's starting quarterback for the rest of this season and beyond.

"When everyone's healthy, everybody's playing well, he's the guy," Nolan said. "But that's not the way it is today.

"I'd like to think he's the quarterback of the future, but he's got to get healthy and get back on the field. With all the talk about his shoulder, this and that, heck, I'm living in today. I don't have time to go there. We've got Minnesota this week."

Dilfer said Smith has remained involved in game-planning meetings and film study and has been helpful in getting him prepared for game day.

But Dilfer, who began the season as Smith's backup and mentor, has had little time to advise Smith on how best to handle his recovery, especially when he's trying to shake off a performance like his four-interception disaster in an ugly loss to Carolina last week.