Zito had his most strikeouts since getting 10 against Atlanta on Aug. 6, 2010.
Padres starter Edinson Volquez struck out six in five innings. He doubled leading off the third and scored on Denorfia's double for San Diego's first run.
Volquez knew Venable was going to make the clutch catch.
"I said, 'That ball, it's not going to bounce,'" the pitcher recalled saying. "He can run. He said he let down the team down because he struck out."
San Francisco shortstop Brandon Crawford went 1 for 6 while batting third for the first time this season.
Bochy was asked before the game why he used Crawford there.
"Crawford asked me the same thing," Bochy said. "I just said, 'Maybe I got into the wine too much last night.'"
NOTES: San Diego is still waiting to determine whether SS Everth Cabrera and OF Carlos Quentin will need a stint on the disabled list. Cabrera came out of Sunday's game after the eighth inning with a left hamstring injury. Quentin missed his third straight game Monday because of left shoulder soreness. ... Giants 3B Pablo Sandoval (strained left foot) and CF Angel Pagan (strained left hamstring) are expected to be activated for the start of a series at Dodger Stadium beginning next Monday. Sandoval played catch and hit in the cage without a walking boot Monday. He is tentatively slated to begin a rehab assignment Friday with Class-A San Jose, and Pagan will likely go out on rehab soon, too. ... San Francisco reliever Santiago Casilla, who had right knee surgery, is expected to throw off a mound within a week. ... San Francisco hosted second-round draft pick INF-RHP Ryder Jones. His late grandfather, Ron Brown, who died last August of cancer, was a huge Giants fan. "This is so cool, because he would have loved this," said Jones' mother, Tiffani, fighting tears in the dugout. ... The Giants are 20-12 against the NL West. ... RHP Matt Cain (5-3) pitches Tuesday night for the Giants against Cashner (5-3).