"On the first swing, it tightened up, then it kind of lingered the rest of the game," Pettibone said. "On that last at-bat, it locked up pretty good. It was more precautionary, so we'll rest it up and see how it feels [Sunday]."
Pettibone pitched six strong innings, but walked off the field with a trainer after he tried warming up for the seventh. The rookie had weakly grounded out to the pitcher to end the sixth inning, and did not make much of an effort to run to first.
Though Pettibone left the contest with a 7-1 lead, the Phillies bullpen imploded and the team needed a walk-off homer from Kevin Frandsen to pick up an 8-7 victory. A win would have been Pettibone's first since May 14, but even without it, he said he was pleased with how his six innings of work went.
Pettibone allowed one run and five hits on 89 pitches (58 strikes), with one strikeout and one walk. It was his first quality start in his past three outings, and he felt like he had more to offer, if it wasn't for his back.
"I thought I could've gone at least another inning, maybe two," Pettibone said. "I always want them to take the ball from me and not give the ball up. So that was frustrating."
Pettibone, 22, has a 4.14 ERA in 67 1/3 innings in 12 outings.
Stephen Pianovich is an associate reporter for MLB.com.
This story was not subject to the approval of Major League Baseball or its clubs.