SANTA CLARA – Josh Johnson returns to the Bay Area this weekend in an enemy uniform, but don't be surprised if he gets a big pregame hug from Jim Harbaugh.

Johnson, the Buccaneers' backup quarterback, played for Harbaugh at the University of San Diego, and Harbaugh has spoken fondly – very fondly – about Johnson since. Harbaugh even called Johnson, who grew up in Oakland, "the beloved son" during an appearance this week on KNBR (680 AM).

"Knowing the competitor Josh is, we'll say hi before the game, give each other a big hug," Harbaugh said. "Then he'll walk away and try to gouge our eyes out. He's like the beloved son. And I hope he doesn't beat us. We'll be trying to gouge his eyes out, too."

Johnson, who played for Harbaugh from 2004 to 2006, left as one of the most accurate passers in NCAA history. Wide receiver John Matthews, added to the 49ers' practice squad this week, was one of Johnson's targets with the Toreros.

"He's got all the ability," Matthews said. "But the thing that I think separated him were his intangibles – his competitiveness, he's a humble guy, likes to spread the ball around and get everyone involved. He's a leader. He leads by example. He just found ways to win."

Johnson, selected by the Buccaneers in the fifth round of the 2008 draft, has been Josh Freeman's backup for the past two seasons. Johnson also was a prolific rusher at San Diego, and Tampa Bay uses him as an occasional Wildcat option. He ran the ball once for eight yards in Monday's win over Indianapolis.

Johnson's background with Harbaugh, and the coach's consistent praise, led to speculation in the offseason the 49ers would try to trade for Johnson. Buccaneers coach Raheem Morris this week declined to say whether Tampa Bay received offers for Johnson during the offseason.

Johnson is scheduled to become an unrestricted free agent after the season, as is 49ers starting quarterback Alex Smith, who is off to his best season in seven years.

The 49ers also used a second-round pick this year on a quarterback, Colin Kaepernick, who has many of the same traits as Johnson.

Fullback update – With veteran fullback Moran Norris (leg) out for Sunday's game and occasional fullback Isaac Sopoaga (staph infection) doubtful, the 49ers have one player at the position: rookie Bruce Miller.

Miller struggled at times in the 49ers' Week 3 win over the Bengals, but he bounced back nicely against the Eagles.

"I've seen an improvement in Bruce every day, really," offensive coordinator Greg Roman said. "He's gotten better since he's gotten here. He's one of those guys that when you correct something, it gets corrected, and you really don't have to revisit it."

The 49ers also have used tight end Delanie Walker in the backfield this season, and they also could do so with tight end Justin Peelle.

Et cetera – Cornerback Shawntae Spencer (toe) is questionable for Sunday's game. Harbaugh said there was a "good chance" rookie cornerback Chris Culliver's role would increase this week.

Frank Gore (knee), Michael Crabtree (foot), Adam Snyder (hamstring) and Mike Iupati (neck) are probable.

• Green Bay's Aaron Rodgers beat Smith in a fan vote for FedEx "Air" Player of the Week honors.

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