"On opening day of Camp Alex II, receiver Michael Crabtree took the field and even caught a few warm-up passes.

Tackle Joe Staley wondered why anyone is surprised.

"He's a great teammate," the lineman said Tuesday after the 49ers renewed their practice sessions at San Jose State. "I think he's a professional. "... He's a very intelligent kid, and he works very hard. You can't say anything about his work ethic."

Earlier this month, Crabtree sat out almost all of the 49ers' player-only practices -- nicknamed Camp Alex because they are organized and led by quarterback Alex Smith. On the first day of that session, Crabtree sustained a foot injury as the result of a problem with new cleats.

On Tuesday, Crabtree remained on the sideline for the early stretching period -- but changed into cleats at the last second and joined teammates for a warm-up session.

The third-year receiver took a cautious approach after that, charting plays with the quarterback group. The media is prohibited from watching practice, but Staley said: "He was going over plays when he wasn't out there running routes. But when we were doing team stuff, he was out there.""