OAKLAND --- The seventh inning was frustrating enough for the Pittsburgh Pirates, but a collision between two players made it even worse.
The Pirates began the frame trailing just 5-4, but the A's scored seven runs en route to a 14-4 win. Perhaps more damaging, though, was Neil Walker's injury, which he suffered in the inning.
With no outs, Oakland's Kevin Kouzmanoff popped the ball up along the right-field line. Right fielder Ryan Church and Walker both charged for it. Walker appeared to hit his head against Church's knee as the ball fell between them.
Walker remained on the ground as the team's medical staff examined him. Minutes later, he left the field on his own power, exiting the game.
Walker was taken to the Alta Bates Summit Medical Center in Oakland for evaluation, but he was coherent and undergoing tests. The club did not disclose the nature of the injury, only that Walker hit his head.
Manager John Russell said that he didn't think Walker lost consciousness. Walker did not move much when he went down.
"He was close," to being unconscious, Russell said. "The initial shock got him. He didn't feel nauseous or anything. We're hoping for the best."
Pittsburgh starter Brad Lincoln, who had just exited the game, said that Walker appeared in the clubhouse after his collision and looked OK.
"He's a tough guy," Lincoln said. "He plays hard and sometimes that happens when you do that."
Following the collision, Bobby Crosby moved from shortstop to second base, and Ronny Cedeno entered the game at shortstop.
Walker was a triple away from the cycle at the time of the injury. He doubled in the first, singled in the third and hit a solo home run in the fifth.