Peavy won't make his scheduled start Tuesday due to a back issue, but hopes to make his next scheduled start Sunday, the San Francisco Chronicle's Henry Schulman reports. He said he's had treatment since his back locked up last week and he feels better, but he's not feeling well enough to take the ball yet. It is not clear who will take Peavy's spot in the rotation Tuesday, as the Giants could move Matt Cain up a day, or they could use some combination of Yusmeiro Petit and Ryan Vogelsong in a bullpen game. Either way, consider Peavy questionable for Sunday's game.