James Shields and Matt Cain are set to take the mound Wednesday as the Padres and Giants face off in the finale of a three-game series at Petco Park. Shields was solid in his first outing after the All-Star break, picking up a win against the Rockies on Friday. Cain is making his fourth start since returning from right elbow surgery and a right flexor tendon strain and will face the Padres for the first time this season.