As other rookies began the 49ers' three-day minicamp Friday, defensive tackle Tank Carradine and running back Marcus Lattimore could only watch practice, restricted by knee injuries that encouragingly are on the mend. Carradine, a second-round pick, and Lattimore, a fourth-round selection, received positive reports after extensive medical exams at Stanford on Thursday. "Everything looks good structurally with all the guys that we drafted," coach Jim Harbaugh said. Carradine, who wore a brace on his right knee, is further along in his rehabilitation from a Nov. 24 torn anterior cruciate ligament. "I'm very anxious, because I'm also coming off the injury and people want to know, 'Would he really be back?' " said Carradine, a Florida State product who's pegged as a backup to Justin Smith and Ray McDonald. Lattimore said Harbaugh "stressed" to take time recovering from his second major knee injury in as many seasons, having torn the ACL in his left knee in 2011. While Harbaugh called it premature to count out Lattimore this season, the coach added: "We're going to have to take a step back in terms of some of the cutting, because we want that inside of the knee to heal fully. But, we're good." Lattimore is OK with sitting out all season if that's what doctors order. "That'll be fine. Whatever happens over the next few months will determine that," Lattimore said. "If I'm called upon, hopefully I'll be ready."