Gronk's back: Star tight end practices with Pats

New England Patriots tight end Rob Gronkowski (87) during an NFL football training camp in Foxborough, Mass., Friday, July 25, 2014. (AP Photo)

Rob Gronkowski is going through light activities at the New England Patriots training camp.

The star tight end ran short routes, caught passes and jogged back to the line of scrimmage during the team's second day of practice.

He's recovering from knee surgery on Jan. 9 so he didn't participate in 11-on-11 drills, cut sharply or run hard at defensive backs.

Gronkowski's not sure he'll play in the season opener Sept. 7, but says he's preparing hard to be ready for it. He's practicing with a brace on his left forearm that was broken in the 11th game of the 2012 and re-broken in the team's first playoff game that season. He also had an elastic sleeve on his surgically repaired right knee.