Red Sox 4, Reds 3 (12): Grady Sizemore drove in the game-winning run to cap a three-hit, two-RBI night as Boston edged visiting Cincinnati.

David Ortiz led off the 12th with a single and Mike Napoli followed with a single up the middle before Sizemore drove a first-pitch fastball from Logan Ondrusek (0-2) off the base of the wall in left to plate Ortiz. Napoli added two RBIs and Dustin Pedroia collected three hits and two runs scored while Craig Breslow (1-0) earned the win in relief.

Homer Bailey allowed three runs in six innings and left the game trailing but the Reds pushed across two runs in the eighth to force extra innings. Brandon Phillips, Skip Schumaker and Zack Cozart each recorded two hits for Cincinnati.

Bailey walked Pedroia leading off the game and he eventually came in to score on Napoli’s groundout to give Boston a quick 1-0 lead. Schumaker’s single plated Todd Frazier to tie it in the second before Bailey struggled again in the third, walking Napoli with the bases loaded to force in a run before Sizemore sent an RBI single through the right side.

Felix Doubront allowed one run in 5 1/3 solid frames but the Reds got to the Red Sox bullpen in the eighth when Junichi Tazawa issued a one-out walk to Joey Votto and a double to Phillips before Frazier delivered an RBI single and Ryan Ludwick followed with a sacrifice fly to knot it up. Boston put three runners on in the ninth but could not push across the winning run.

GAME NOTEBOOK: Reds CF Billy Hamilton did not start the game due to a sprained left middle finger but appeared as a pinch hitter in the ninth and put down a sacrifice bunt. … Cincinnati LHP Aroldis Chapman (head) made a rehab appearance with Triple-A Louisville on Tuesday and is expected to rejoin the team this weekend. … Boston RHP Edward Mujica (oblique) threw before the game and could avoid a stint on the disabled list.