Ian Stewart led off the 12th inning with an opposite-field homer to lift the Colorado Rockies to a 6-5 victory over the host San Diego Padres on Wednesday night.

Stewart’s homer, his second of the year, was the first run allowed by Padres reliever Tim Stauffer (2-1) this season in 18 1/3 innings.

Manny Corpas (1-1) pitched 2 2/3 innings of scoreless relief for the victory.

San Diego scored four runs in the fourth to take a 5-3 lead. Kyle Blanks and Jerry Hairston Jr. each singled in a run and pitcher Clayton Richard doubled in two.

Colorado tied the score in the sixth on Clint Barmes’ run-scoring double and Seth Smith’s pinch-hit triple.

The Padres struck first on Blanks’ second-inning double before Colorado scored three times in the third. Melvin Mora drew a bases-loaded walk and Barmes singled in two runs.

Both starting pitchers lasted five innings. San Diego’s Richard gave up three runs and six hits with five walks and five strikeouts. Colorado’s Aaron Cook allowed five runs and six hits. He walked two and struck out two.