Charlie Morton returned to Pittsburgh Saturday so team doctors could examine his right shoulder, which tightened on him during his rehabilitation start Friday night.
Morton, near the end of his recovery from Tommy John ligament replacement surgery, said he could not get his shoulder loose while warming up before the third inning of his start for Class AAA Indianapolis.
"It was the kind of thing where it was a different sensation than I had experienced," Morton said. "It kind of threw up a red flag. I just told them, I couldn't get loose, I'm tight."
Morton met with the team trainers Saturday, but the Pirates' medical staff had not yet examined him.
"They don't seem to think it's serious at all," he said. "I'm not expecting anything bad really. I think a lot of it was just precautionary and a bump in the road.
"I could probably go out there and play catch and go through the motions. The challenge is getting off the mound and getting the velocity back up."
Morton's outing Friday was his fourth rehab start. His 30-day rehab assignment ends May 17, but the Pirates can halt the clock if they choose. Morton was on track to return in mid-May, about 11 months after the June 14 surgery that ended his 2012 season.
In conversations with doctors and other pitchers who have had Tommy John surgery, Morton said, he understood the difficult nature of the recovery process.
"I wanted the journey to be serene and quaint and just peaceful," he joked. "I think that's also something that you appreciate about this whole thing is that its not easy, it's not simple, it's not short and sweet. It's difficult. I'm not surprised. I was kind of irritated."
Morton allowed one run on two walks and no hits before leaving the Friday game. In 16 innings of rehab appearances, he has allowed four runs, three earned, on seven hits, with five walks and 10 strikeouts. Two of those runs came in one three-inning outing with Class A Bradenton.
"I've been getting good results," Morton said. "I pitched a game in Bradenton I'd like to have a couple pitches back. I'm really just testing the waters, so to speak, with my stuff to see how the hitters are reacting.
"[Friday] night I walked out to the field and I was good. I felt good to go. I was looking forward to competing. As opposed to going out there and I'm thinking mechanics, I'm thinking this or that."
Morton said he was aware of the other factors influencing his eventual return to the Pirates. Barring another injury, the Pirates must remove someone from the rotation to add Morton.
"It's a setback for my readiness if it alters my schedule, which I'm assuming it would," Morton said. "I'm not sure how much that would affect my return to the big leagues. My return is dependent on many more factors than my readiness."
Next step for Karstens
Jeff Karstens, who has battled a sore shoulder this spring, said he will travel to Bradenton, Fla. Monday and has two outings scheduled. He will pitch in extended spring training Wednesday and for Class A Bradenton May 13.
Karstens pitched a two-inning simulated game Friday, using all his pitches, and said he felt good.
Bill Brink: email@example.com and on Twitter @BrinkPG. First Published May 5, 2013 4:00 AM