"It's very minor. We'll take a few days and re-evaluate," Locke said. "It's funny. I was just out there throwing normally. It could be I was coming out of my turn quick. It could be I didn't stretch enough."
Locke was an All-Star last year but didn't pitch due to a back injury. He struggled in the second half - at one point he was sent to Double-A - and finished 10-7 with a 3.52 ERA. He is battling Edinson Volquez for the No. 5 spot in the rotation.
"From what I've heard from the training staff, it's something that if we don't take care of it now, it could be six to eight weeks later," Locke said. "That's something I can't afford."
Pirates left-hander Jeff Locke does not expect to miss much time due to tightness in his right oblique. Locke felt what he said felt like "a continuous little pull" during his last bullpen session and was scratched from his scheduled start Wednesday.
Lefty has oblique tightness.