Roy Oswalt (hamstring) allowed three hits and a walk over 5 2/3 scoreless innings in a rehab start with rookie league Grand Junction Rockies on Tuesday. He struck out a pair, throwing 41 of 55 pitches for strikes. Manager Walt Weiss indicated that how Oswalt fares Tuesday will determine what role he'll serve in for the team down the stretch. It's probably safe to say he'll rejoin the rotation next week.