Mathieson returned to the field at the end of the 2007 season after nearly a year off, but he pitched just eight innings before the Phillies shut him down to have a second elbow surgery. Last week, Mathieson threw off the mound for the first time since his second surgery, tossing 20 pitches in a bullpen session.

"Once I got out of the stretch and started throwing from the windup, I was like ‘This feels good – finally,’" said Mathieson, who first went under the knife in September of 2006 with Tommy John surgery.

"He was fine – he had a nice, controlled velocity and after 20 pitches," added Phillies pitching coach Rich Dubee, who watched over the right-hander’s shoulder Tuesday morning. "His arm seemed to be working fine and he didn’t have any different feeling from his long toss to his mound work, so that was good."

Mathieson is the No. 12 prospect in the Phillies system.