ST. LOUIS -- Russell Martin was back in the Pirates' clubhouse Sunday morning, feeling better both physically and emotionally.

On the body side, pain in the left hip area deriving from having favored a strained left hamstring had subsided. On the soul side, an MRI confirming the hamstring as the only issue came as relief.

"The MRI just showed a strain in the hammy," said Martin, who went on the disabled list Saturday and also went to Pittsburgh for the medical evaluation. "With the hip [discomfort], I was probably complicating things trying to take away some of the pain from the hammy. The only thing sore now is the hammy."

Martin received a platelet-rich plasma injection, and will rest for a few days before beginning a rehab routine laid out by head athletic trainer Todd Tomczyk.

The veteran said he has dealt with the hamstring discomfort since the onset of Spring Training.

"Even coming into Spring Training, I felt there was some tightness," Martin said. "I didn't know the severity, but I managed it pretty well through Spring Training. You don't play every day, and you don't play nine innings, so you can grind through it."

Martin sensed he was in serious trouble on April 19, when he tore down the first-base line for an infield single after lining a ball off Milwaukee pitcher Rob Wooten -- and three pitches later raced home on a double by Andrew McCutchen.

"I knew something was wrong, that I'd re-tweaked it pretty badly," said Martin, noting that since the mere act of checking swings had been excruciating. "I would really feel a jolt. With every checked swing, it would get worse and worse."