The Washington Nationals are limping toward the National League (NL) East title with star Daniel Murphy missing his fourth consecutive game because of an unspecified left leg injury.

Manager Dusty Baker hopes Murphy, who hurt his leg on Saturday after sliding into second base for a double, can return for the opening of a three-game series in Atlanta on Friday.

Baker initially said Murphy hurt "his buttocks" but since, the manager and the club have not officially identified the injury.

"He hasn't been responding to treatment," Baker told reporters on Wednesday.

"With a day off [Thursday], we'll work on it. We'll work on it and see. Our trainers are still working on him.

"They are trying to get to the bottom of it. When you are hurt this late in the season, you don't have a bunch of time to come back. We have some hands working on him."

Murphy has 25 homers and 104 RBIs but the Nationals are 8-9 in games that he has not started this season, including the previous three consecutive losses.

"You're always a little concerned about a player of Daniel's ability," Baker said.

"Concern really doesn't help the situation. If concern or worry would help, I'd be worrying all day and night and they'd be better, but it doesn't help.

"What you have to do, everybody else has to do a little more because Daniel has been carrying us most of the season.

"Now it's time for some of the other guys to step up in Daniel's absence."

The Nationals entered Wednesday's game with a magic number of four to clinch the NL East over the New York Mets.