Promising rookie defensive end Nick Bosa undergoes MRI revealing sprained ankle

SANTA CLARA - The 49ers had an unwelcome sight on the practice field Wednesday.

Talented rookie defensive end Nick Bosa, who has been one of San Francisco’s most prominent bright spots throughout the first nine training camp practices, walked off the field after suffering an apparent lower right leg injury.

Defensive coordinator Robert Saleh didn’t have an immediate prognosis on Bosa’s injury after practice, but he did acknowledge the No. 2 pick in April was making a sizable impact in the early going.

“He’s been progressing very well,” Saleh said. “Very pleased with him. He’s gotten back to the pass rush, he’s been very good in the run game. At this point, he’s progressed very well overall and we’re very excited about him.”

Bosa appeared to get tangled up during a running play roughly two-thirds of the way through the padded practice and stayed on the ground where members of the training staff looked at his right foot and ankle area. After a few moments, he slowly stood up and began walking gingerly off the field to go inside for further testing.

Bosa, 21, was the first defensive player taken in the NFL draft after a promising career at Ohio State. However, there were questions about his health coming after a core muscle injury in the third game last season prevented Bosa from finishing out his college career with the Buckeyes.

He elected to have surgery and focus on preparing for the draft rather than risk further injury in college. He later missed the bulk of San Francisco’s offseason program with a mild hamstring strain.

Bosa appears to be offering the 49ers a significant upgrade at defensive end after the team struggled to bother opposing quarterbacks in 2018. He joined Dee Ford, who came via trade from the Kansas City Chiefs, as the most notable additions to a new-look defensive front.

The defensive line has become the strength of San Francisco’s defense, though it’s currently dealing with a slew of injuries with the regular season opener a month out. Ford has missed most of the last week with knee tendinitis while backup Ronald Blair III sat out Wednesday’s session with a groin injury. Additionally, former first-round draft pick Arik Armstead was a late scratch with a calf injury, the 49ers said.

The injuries led to budding star defensive tackle DeForest Buckner spending most of the practice working at defensive end, where he’s seen scant reps during his three NFL seasons.