Arizona Wildcats defensive tackle Willie Mobley will miss the start of the 2011 season, and could be out longer, after suffering a severe knee injury.

A UA spokesman confirmed this afternoon that Mobley tore his ACL playing basketball at the campus recreation center. He will undergo surgery soon, and could be out as long as six months.

Coaches were expecting big things from Mobley, a transfer from Ohio State who was expected to back up starter Justin Washington (Justin Washington) this fall.

Mobley played in 10 games as a sophomore in 2010, registering seven tackles and 1.5 tackles for loss and half a sack. The 6-foot-2-inch, 280-pound Mobley had three tackles in last month’s spring game.

Mobley is the fourth UA player to injure his ACL this spring. Safety Adam Hall, running back Greg Nwoko and linebacker Jake Fischer are all expected to miss the start of the season after suffering knee injuries in spring drills.