Roy Oswalt (back) will begin a rehab assignment Wednesday with Triple-A Lehigh Valley. He's expected to throw 60 pitches. Oswalt had an impressive bullpen session Friday and thinks he'll need just the one rehab start, but it's possible he could require more. The limited pitch count would seem to suggest an additional start will be needed. Assuming all goes well, he should return sometime in early August. The veteran has been sidelined since late June.