WASHINGTON -- Phillies third baseman Pedro Feliz was diagnosed Thursday with a bulging disk in his back, the club announced.

Placed on the disabled list Tuesday, Feliz underwent a series of tests, including an MRI and an examination by a back specialist at Thomas Jefferson University Hospital. He won't participate in baseball-related activities until next week, at the earliest.

Feliz missed the weekend series against the Braves and hopes he could play on Tuesday, but he experienced discomfort throwing Sunday and hasn't swung a bat in at least a week. He had told manager Charlie Manuel that he began to feel something during the trip to Oakland and Texas at the end of June.

The injury could keep Feliz out beyond Aug. 9, when he is eligible to be activated from the disabled list. He is batting .256 with 12 homers and 41 RBIs.