Cavaliers All-Star forward LeBron James has been hospitalized for tests on a strained chest muscle he doesn't know how he injured.

James was admitted to the Cleveland Clinic on Wednesday night as he continued to experience discomfort for what has been diagnosed by team doctors as a strained left pectoral muscle. The team didn't reveal James' hospital stay until Thursday when the 20-year-old did not practice with the Cavaliers.

Cavaliers general manager Danny Ferry said all the preliminary testing done on James has been normal. Ferry hopes James can be released on Thursday. The Cavaliers have a home preseason game Friday night against Philadelphia.

James did not play in Cleveland's game Tuesday night in Pittsburgh because of the muscle strain. He was visibly wincing in pain during Wednesday's workout at Quicken Loans Arena, and afterward said he didn't know how he hurt his chest.

"I don't remember getting elbowed in the chest or pushed," said James, who scored 16 points in game Monday night against Washington. "It was something I never felt before."