OAKLAND, Calif. (AP) _ Center fielder Ellis Burks of the Boston Red Sox sustained a slightly separated right shoulder in a full-speed collision with teammate Mike Greenwell in the fifth inning of Wednesday's game with the Oakland Athletics.

Greenwell, who bruised his ribs, stayed in left field but left the game two innings later.

The collision occurred as the two players were chasing leadoff batter Dave Parker's fly ball to left center. Burks, who went 3-for-3 to extend his hitting streak to 15 games, caught the ball and the two players slammed into each other and fell to the ground.

Greenwell, who had a double and an RBI, sat up about a minute later. Burks got up minutes later and jogged back to the dugout.

''We just didn't hear each other,'' Greenwell said. ''The center fielder definitely has priority, but I called him off and kept coming, so did he, and we collided.''

He said he decided to come out after his side tightened, but hopes to play in the Red Sox' next game Friday night in Anaheim.

Boston manager Joe Morgan said he thought the play was Greenwell's all the way.

''It seems like Burks can't stay away from injuries,'' he said. ''We just have to pick up the pieces and go on from here. We've had them both injured before.''

Burks, who's hitting .303 with 12 home runs and 61 RBIs, underwent arthroscopic surgery June 21 for torn cartilage in his left shoulder after being injured while trying to make a diving catch against Detroit.

Last year he had arthroscopic surgery to remove bone chips from his right ankle during spring training and later missed time due to left wrist problems.

Other Red Sox injured this year include Dennis ''Oil Can'' Boyd, John Dopson, Marty Barrett, Dwight Evans, Greenwell, Jim Rice.

''It could get worse,'' Greenwell said. ''The plane could go down.''