Phillies placed RHP Roy Oswalt on the 15-day disabled list with lower-back tightness. The move ensures that Oswalt will miss at least his next two starts, while buying the Phillies time to figure out just how severe his injury really is. He is set to undergo an MRI on Monday. Scott Mathieson will take his place on the 25-man roster, while both Kyle Kendrick and Vance Worley should now remain in the Phillies rotation for the foreseeable future.