PHOENIX -- Washington catcher Matt Wieters was removed from Thursday's 2-1, 11-inning win with a left leg injury after singling to center field to open the second inning.
Wieters is set to undergo an MRI on Friday.
"The step before the bag, I kind of felt behind the knee go a little bit," he said. "It didn't feel any better after a few more strides. We're thinking it's probably a hamstring, but it is in the back of the connection point where there are some others running there.
"Hopefully, it is the hamstring, and hopefully it is not too bad."
Wieters grounded a single up the middle off Zack Greinke and appeared to pull up as he rounded first base. Trainer Paul Lessard came out of the dugout to tend to Wieters, and manager Dave Martinez also ran onto the field before signaling for backup catcher Pedro Severino to pinch-run.
Wieters is hitting .231 with three homers and seven RBIs in 65 at-bats.
Severino, a .268 hitter, is the only other catcher on the roster.