Bay hit a two-run home run before winning it in the 14th inning with a long single against a drawn-in outfield and the Pirates beat the Cubs, 5-4, Saturday night.
Freddy Sanchez reached when shortstop Ryan Theriot threw wildly on his grounder to start the 14th and moved up on a wild pitch. After he took third on a grounder and Nate McLouth was walked intentionally, Bay lofted a fly close to the warning track in center to win it.
"It was my first RBI single of the year -- and it could have been a double if it hadn't been a walk-off [situation]," Bay said, referring to the scoring rule that counts all such game-winning hits as singles. "Regardless of how it happened, it's a win and I'm excited."