Jesus Guzman snapped a tie with an RBI single as the San Diego Padres dealt a blow to San Francisco's postseason hopes with a 3-1 victory over the visiting Giants on Wednesday.

The Giants fell seven games behind the National League West-leading Arizona Diamondbacks, who defeated the Colorado Rockies 5-3.

After Will Venable wrapped a homer just inside the right-field foul pole in the first, the Padres didn't muster another hit off Matt Cain (11-10) until Cameron Maybin ripped a double in the sixth.

Guzman's single to left field plated Maybin to give San Diego its second win in 13 games against San Francisco.

Venable preserved the slim advantage by throwing out rookie Brett Pill at home to end the seventh and Maybin added an RBI triple in the eighth.

Aaron Harang (13-5) snapped a modest two-game losing skid by allowing one run on four hits in seven innings. Chad Qualls bridged the gap to Heath Bell, who recorded the final four outs for his 36th save.

After homering in his first major league at-bat Tuesday, Pill went deep again in the fifth for San Francisco.

Cain, making his 200th career start, fell to 2-6 against the Padres after permitting two runs on four hits in seven innings and 68-72 in his career.