With Kevin Kouzmanoff at the plate for Oakland, Yankees starter Javier Vazquez delivered a 1-0 pitch to the A's third baseman, who fouled the ball back toward Rapuano.
Rapuano stayed in the game for one more batter before being checked. The game was delayed for 13 minutes, and Rapuano was replaced behind the plate by second-base umpire Ron Kulpa. No one stepped in to fulfill second-base duties.
An alert Rapuano was taken by ambulance to nearby Summitt Medical Center to undergo a CT scan.
Jane Lee is a reporter for MLB.com. This story was not subject to the approval of Major League Baseball or its clubs.