During the next few days, the Pirates must navigate the uncertainty caused by a tight hamstring, a stretch of 20 games in a row without a day off and a possible impending roster move.

The Pirates had not received the results from the MRI exam on left-handed pitcher Wandy Rodriguez's left hamstring by Tuesday evening. It tightened on him in the third inning Monday night, forcing him to make an early exit.

As manager Clint Hurdle and his staff decide their next step, they must wait for Rodriguez's condition to be clarified while keeping the workload of the rest of the rotation under consideration.

A.J. Burnett will start Friday at home against the Cincinnati Reds, Hurdle said, and Jeff Locke will start Saturday. James McDonald will open the series Monday against the St. Louis Cardinals, also at home, and Jonathan Sanchez will start Tuesday. Each pitcher will start on five days of rest, one more than usual.

"I have every inclination to keep McDonald and Sanchez in place [against] St. Louis," Hurdle said. "I don't want to move them up to them having four days' rest. We want everybody that pitches as we walk into this next 20-game set to have an extra day."

That leaves Sunday open, and the Pirates are waiting to see if Rodriguez can pitch Sunday before making a decision.