Cameron Maybin, truth be told, has not been sold on this whole umpire-challenge and instant-replay thing. Not even close.

"Now I am," said the Padres center fielder. "Today."

"Today," meaning Sunday, the day an overturned call enabled Maybin to be in position to score the walk-off run in a 4-3 win over the Arizona Diamondbacks. Maybin, who ended the game at Petco Park with a sprint home on Yonder Alonso's one-out, ninth-inning dribbler to the right side, had reached base only after manager Bud Black's second successful challenge of an umpire's call and the use of instant replay.

First-base ump Bill Welke incorrectly had called Maybin out on a barehanded catch-and-throw by Arizona second baseman Aaron Hill, and because he'd been right with his first challenge, Black had another one coming to him. And after Rene Rivera doubled the speedy Maybin to third, even a barehanded grab of Alonso's grounder left first baseman Paul Goldschmidt no realistic chance of getting Maybin at the plate.