"It's a little tight just grinding through these past couple days -- starting to throw bullpens, stretching out my long toss and everything," Pettibone said on Saturday at Bright House Field. "It's come along great. We haven't had any setbacks, so that's definitely a positive."
Pettibone, 24, will throw his third bullpen session on Sunday. He is expected to remain in Clearwater once the season starts to make a few starts before he joins Triple-A Lehigh Valley. From there, he hopes to begin his road back to the big leagues -- where he posted a 4.04 ERA in 100 1/3 innings as a rookie.
"Anytime after surgery, you're kind of uneasy about the whole situation," said Pettibone. "But I've been kind of staying positive."
• The Phillies play the University of Tampa on Sunday afternoon in an exhibition at Bright House Field.
Rule 5 Draft pick Odubel Herrera will hit leadoff and play center field. Cesar Hernandez (second base), Cord Phelps (third base), Darin Ruf (left field), Chris McGuiness (first base), Russ Canzler (designated hitter), Aaron Altherr (right field), Tommy Joseph (catcher) and Chase d'Arnaud (shortstop) follow him in the lineup.
Right-hander Paul Clemens will start.
"He's a guy that has a little bit of starting experience," Phillies manager Ryne Sandberg said. "He could be a long-man type of guy."
Todd Zolecki has been the Phillies beat reporter for MLB.com since 2009, and has been covering the Phillies since 2003.
This story was not subject to the approval of Major League Baseball or its clubs.