"I felt soreness late in the game, a little hamstring soreness," Murphy said after the Nationals' 5-1 win on Friday.
Baker then told Clint Robinson to be ready to start. Robinson ended up going 2-for-4 with an RBI in the victory over the Pirates.
"This is a deep group of position players. It was a great lineup and Clint swung the bat well," Murphy said.
During the first half of the season, Murphy helped carry the Nationals into first place in the National League East. Murphy hit .348 with 17 home runs, 66 RBIs and a .387 on-base percentage, earning a spot in the All-Star Game, in which he went 2-for-3.
Bill Ladson has covered the Nationals/Expos for MLB.com since 2002 and writes an MLBlog, All Nats All the Time. He also can be found on Twitter @WashingNats. This story was not subject to the approval of Major League Baseball or its clubs.