An out-of-line fan sitting near the A's dugout Wednesday afternoon at Angel Stadium threw a plastic water bottle and struck Mike Piazza in the head, prompting the A's designated hitter to promise legal action. The incident happened in the top of the ninth inning as the A's were mounting a comeback against Los Angeles Angels closer Francisco Rodriguez. Piazza was standing in the on-deck circle when he was plunked in the back of the head by the bottle. He walked toward the fan and continued pointing his bat at the man to identify him to security. The fan made a hasty journey up the stairs but was met by security and was being detained after the game.