Giants 6, Padres 0: Hector Sanchez drove in three runs and emergency starter Yusmeiro Petit tossed six shutout innings as host San Francisco blanked San Diego.Angel Pagan and Buster Posey hit solo homers and Brandon Crawford added a run-scoring single for the Giants. Petit (2-1) struck out four and gave up three hits without a walk while replacing injured Matt Cain.Petit learned he was starting approximately an hour before the start after Cain cut his right index finger with a knife. He departed after 72 pitches and Jean Machi pitched two shutout innings and Santiago Casilla finished up.Pagan and Posey each hit first-inning homers off Eric Stults (1-3) to get the Giants started and San Francisco added three more runs in the third. Sanchez smacked a two-run single to center to make it 4-0 and Crawford followed with an RBI single to right.Sanchez hit a sacrifice fly to left in the sixth to make it a six-run margin. Machi and Casilla then combined to retire all nine hitters they faced to complete a three-hit shutout. GAME NOTEBOOK: Cain was injured in the clubhouse kitchen after batting practice when a knife slipped out of his hand and he gashed the finger while trying to grab hold of it. … Stults allowed five runs and seven hits in 2 2/3 innings. … Padres OF Seth Smith struck out as a pinch hitter in the ninth in his first appearance since suffering a groin injury Thursday.