The injury came after Hicks tried to beat out a soft grounder to third base in the top of the fifth inning. Hicks was thrown out by Ryan Zimmerman on the play and went back out to center field for the bottom of the inning.
But with right-hander Samuel Deduno pitching to Roger Bernadina, a sudden downpour fell on Nationals Park to force a short delay. When play resumed, Thomas replaced Hicks in center.
"It's a strained hamstring,so I'll be reevaluated tomorrow," Hicks said. "I felt it when I hit the bag. I tried to play and then the rain came down and I came back in, and I was told to ice up."
Rhett Bollinger is a reporter for MLB.com. Read his blog, Bollinger Beat, and follow him on Twitter @RhettBollinger. This story was not subject to the approval of Major League Baseball or its clubs.