SANTA CLARA -- Running back Marcus Lattimore is coping with a minor injury not related to his surgically repaired right knee, coach Jim Harbaugh said.

Harbaugh declined to reveal any further details about Lattimore's injury. The former South Carolina running back did not play in his 2013 rookie season while recovering from a gruesome knee injury in October 2012.

"We're going to be going at a speed the doctors allow him and his body allows him to go," Harbaugh said. "The days he was full speed, he looked very good."

  • Defensive back Jimmie Ward, the 49ers' first-round draft pick, will be restricted to individual drills this minicamp because of foot surgery in March. Harbaugh expects him fully healthy by the start of training camp in two months.

  • Tailback and return specialist LaMichael James participated this week in the offseason program, which he missed the start of while training in his native Texas.

  • Marcus Martin, a third-round pick out of USC, may be a contender to start at center, but he's currently just an "understudy," Harbaugh said.

    Martin said his best tutors have been his fellow linemen, including Anthony Davis, who started as a rookie at age 20, as could be the case for Martin.

    "One thing Anthony emphasized was that age doesn't have anything to do with how you play on the field," Martin said.

    Daniel Kilgore is the frontrunner to start at center in place of Jonathan Goodwin, who's a free agent after three seasons with the 49ers.

    Martin sounded comfortable with adapting to the 49ers' system: "It's coming along pretty smoothly. It's pretty similar to the system I ran in college."

  • Guard Brandon Thomas, a third-round pick recovering from knee surgery, became the 10th draft choice to sign from the 12-man class.

  • Wide receiver Jerry Rice Jr. said "everyone has been respectful" in the locker room regarding his auditions with the 49ers, as well as last week's with the Baltimore Ravens. He is wearing No. 83, having declined the 49ers' offer to wear his dad's retired No. 80.

  • Among the 15 players trying out is long snapper Jimmy Davenport, the grandson of former Giants third baseman and manager Jim Davenport. The younger Davenport attended Newark Memorial High, played four yours in the Seattle Mariners' farm system and resumed his football career at Chabot College and Faulkner University in Alabama. Davenport said he was a "little starstruck" seeing Harbaugh.

  • Cornerback Dontae Johnson can't use his 6-foot-2, 200-pound frame this minicamp to show off his press coverage skills, seeing how no-contact rules are in effect. "But come the OTAs and training camp, I plan to work on that," said Johnson, noting he's studied the forms of Champ Bailey and Richard Sherman.