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SANTA CLARA – Rookie defensive end Nick Bosa sustained a right hamstring injury during practice Tuesday and sat out the remainder of the 49ers’ second session of organized team activities.

“It was a hamstring,” 49ers coach Kyle Shanahan said. “Don’t know the severity of it.”

Bosa, the No. 2 overall draft pick, lined up at right defensive end with the second team in an 11-on-11 drill early in practice. He sat out the remainder of the hour-long practice after feeling discomfort in his hamstring. When the offensive and defensive lines ran at the end of practice, Bosa did not take part in the conditioning.

The 49ers return to practice on Thursday to wrap up the first week of four consecutive weeks of on-field work. At the conclusion of the offseason program, the 49ers will take a six-week break before reporting back for the start of training camp. The 49ers can be expected to take no chances with Bosa during the offseason program to increase the odds he is healthy at the start of training camp.

Bosa sustained a bilateral core muscle injury in the third game of last year and underwent surgery, bringing his final season at Ohio State to an early end.