Quentin unloaded a two-run blast in the fifth inning and ignited a four-run uprising in the third with a run-scoring double as the Padres banged out 12 hits.
Nick Hundley (3-for-4, two RBI), Chris Denorfia (three runs scored) and Wil Venable (two RBI) each supplied a solo shot for the Padres, who rebounded after being no-hit by the Giants' Tim Lincecum Saturday.
The victory was only the second in 16 games for San Diego, which avoided a four-game sweep.
Eric Stults (8-7) allowed one run on five hits over six innings, walking two and striking out five.
Giants starter Barry Zito (4-7) lasted just two innings, allowing four runs on four hits, including three homers.
Marco Scutaro provided the only RBI for San Francisco.