The walk, the third by losing pitcher Franklin Morales (3-1), broke a 2-2 tie to end the game.
Adrian Gonzalez had two hits and one RBI, and Chase Headley hit a sacrifice fly for the Padres, who have won 12 of their last 17 games, but are long out of the post-season picture.
The winner was Sean Gallagher (1-0).
Troy Tulowitzki and Yorvit Torrealba had two hits and one RBI apiece for the Rockies, who fell three games behind Los Angeles in the National League West, but stayed 5 1/2 games ahead of San Francisco in the wild-card race.
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