SANTA CLARA (CBS SF/AP) — As the San Francisco 49ers training camp moved into full gear, there are a lot of eyes on star defensive end Nick Bosa as he comes back from missing most of the 2020 season with a serious knee injury.

While there’s great optimism, head coach Kyle Shanahan remains cautious as to just when the defensive star will return to full contact.

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“We’re taking it really a block at a time,” Shanahan said. “We haven’t set a date where, hey, this is the day you start…I’m going to count on Nick on that the most. I know Nick, we don’t have to make a lot of decisions for him when it comes to football. He’s thinking about his body and what’s right 24-7. I think it’s tough when you’ve got younger guys that you need to develop a lot and also protect. But as I joked with Nick, I feel like he’s been developed as a pass rusher since he was like three, so he’s been focused on it. It’s a little bit easier with him.”

The San Francisco defensive end was a limited participant in the team’s first two practices of training camp, followed by a maintenance day Friday. The knee has held up well to this point, putting Bosa on track to play in the Sept. 12 season opener against the Detroit Lions.

“I knew when it was an early injury (last season) that I’d, for the most part, probably be ready to go for Week 1, and everything right now is trending towards that,” he said. “So I’m hoping to ramp it up as I go and be ready to give it all I got for Week 1.”

Bosa took the league by storm in 2019, recording 47 tackles, nine sacks and 16 tackles for loss. For his efforts, he was named the NFL’s Defensive Rookie of the Year.

But in just Week 2 of the ’20 season, Bosa tore the ACL in his left knee.

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“You come off 2019 and you’re on top of the world, and then you start off well in your next season and it’s all taken away really quick,” he said. “It was tough. Mentally, it’s really rough and when your body feels terrible, your mind kind of goes to that place.”

Bosa, 23, found a way to stay positive throughout the rehab process and his hard work has paid off. He says the knee has responded even better than he could have imagined.

“I’m moving better than I ever have right now,” Bosa said. “I’m very confident in how I’m going to feel out there on the field this year.”

Bosa’s return, along with that of fellow defensive end Dee Ford, who missed the final 15 games last season with a back injury, is already bringing back memories of San Francisco’s dominant defensive line in ’19. That unit led the team to 13-3 record and a trip to the Super Bowl.

“They’re going to be nice,” safety Jimmie Ward smiled. “I think they’re going to have their own identity. They’re going to be a great unit.”

Linebacker Fred Warner echoed that sentiment.

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“It’s just good to have (Bosa and Ford) back,” he said. “Having them back just gives not only a boost to the whole defense but to the entire team.”