SANTA CLARA (AP) — Running back Marcus Lattimore might be the most publicized second-year player for the San Francisco 49ers who sat out as a rookie because of a knee injury. Another player from that class — and an even higher draft pick — rehabbing with Lattimore last season is poised to make an even bigger mark.

Tank Carradine missed all of last year recovering from a torn anterior cruciate ligament in his right knee suffered at the end of the 2012 season with Florida State. There were times, Carradine said, he questioned whether he could ever play at the level that made him the 40th overall draft pick again.

The 6-foot-4, 273-pound defensive lineman leaned on Lattimore every morning he walked into the training room.

“We talked about it all the time,” Carradine said Wednesday, the second day of San Francisco’s three-day mandatory minicamp. “Every day we asked each other how we feel and then we just kind of made it like a joke when we see each other. He ask me how I feel, I ask him how he feels and everything. But we talked about it and always said, ‘We couldn’t wait for the opportunity.’”

Healthy again, that chance has finally arrived.

Carradine is getting extra repetitions in practice this week because veteran defensive tackle Justin Smith is out with an unspecified injury. Coach Jim Harbaugh said Smith is expected back for the start of training camp next month.

The 49ers initially thought Carradine could contribute late last season when they drafted him as a defensive end in Florida State’s 4-3 scheme. General manager Trent Baalke said he loved the versatility Carradine could bring to San Francisco’s 3-4 defense playing in several spots in various packages.

Instead, coaches felt Carradine could not get the force he needed from his knee in practice and shut him down in November. That’s when Carradine’s concerns began to mount.

“I was worried last year because I didn’t feel like myself,” he said. “I felt like my knee was strong, but I didn’t feel like myself. I didn’t really know if I was ever going to be the same again. I also heard stories of guys who tear knees, they come back and they’re just not the same.”

Carradine said an MRI exam at the end of the year revealed a buildup of scar tissue, and in January he had a procedure to clean it out. He said he felt the difference almost immediately.

“I felt like I was 100 percent,” he said. “I was able to get full range of motion on my knee, I was able to bend it and then also got my strength back on my leg. Now I feel like I’m back to normal again.”

Carradine is expected to take over the role most figured he’d have last year: as a backup to Smith and Ray McDonald on the outside of the line. He will also compete against more experienced players such as Demarcus Dobbs and Tony Jerod-Eddie.

While Carradine said sitting out last year gave him an opportunity to learn assignments and technique, defensive coordinator Vic Fangio said Carradine still has a lot of catching up to do on the field.

“He’s basically not much different than a rookie coming in right now,” Fangio said. “So this is his first shot.”

At the very least, Carradine’s injury has given him a new perspective — one that he will carry with him on the field every down.

“I learned that you never know when it’s your last play,” Carradine said. “You can go out there and everything can be going good and you can be having an amazing season and things like that and then all of the sudden you have a knee injury and it’s out. I just learned to take advantage of every opportunity.”