Morton will undergo an MRI on Saturday after leaving his start Friday at Washington with right index finger discomfort, Mark Bowman of MLB.com reports.
Morton felt something in his right index finger while throwing a curveball in the bottom of the first inning and was replaced by Michael Tonkin before the bottom of the second. X-rays were negative for any fractures, but Morton may be dealing with some sort of ligament or tendon issue -- for now, it's being called a sprain. This injury could mark the end of his regular season if it's at all severe, though he still might be a possibility for the NLDS. His final regular-season start was slated to come in next week's series in Atlanta against the Cubs.