"He just strained his groin a little bit, so we took him out, making sure he didn't do anything further," Williams said. "We'll see how he wakes up tomorrow and how he feels. So we'll have more information on that in the morning. He says he feels OK, but we'll see how he wakes up, how sore he is tomorrow."
Escobar has gotten off a strong start for his new club. He finished 1-for-3 on Friday, hitting out of the leadoff spot, and is batting .286/.362/.405 with two doubles and one home run. His first-inning single extended his streak of reaching base safely to 10 games.
With Anthony Rendon still on the disabled list, the Nats will face a bit of a roster issue if Escobar is sidelined as well. With Espinosa replacing him at third, the only other player on the active roster with experience at that position is Ryan Zimmerman, who shifted to first base this year due to shoulder problems that affected his throwing.
The only other option on the 40-man roster is Wilmer Difo, who is playing at Class A Advanced Potomac. However, the Nats can open up a 40-man spot for a player from Triple-A Syracuse, such as Ian Stewart, by shifting injured reliever Craig Stammen to the 60-day DL.
Center fielder Denard Span played nine innings in center field and went 1-for-4 with a walk in a rehab game for Class A Hagerstown on Friday night. Span, who played seven innings for Hagerstown on Thursday, experienced "no issues," according to Williams. He will be at Nationals Park for a workout on Saturday, and if he still feels fine, could be activated from the DL as soon as Sunday.
Andrew Simon is a reporter for MLB.com. Follow him on Twitter @AndrewSimonMLB. This story was not subject to the approval of Major League Baseball or its clubs.