. (AP Photo/Alex Brandon)

Nationals right-hander Doug Fister took a “good step” in his rehab from a lat strain today when he pitched off flat ground at Nationals Park, Manager Matt Williams said.

Fister had played toss from 120 feet, but he had yet to replicate his pitching form. Williams said Fister “feels good.” Fister could throw a full bullpen session either Friday or Saturday, depending how he feels, Williams said.

Fister, the prized offseason trade acquisition, strained his lat pitching in a minor league game March 27, after he had spent most of spring training recovering from elbow inflammation. The Nationals expect Fister to return from the disabled list either in late April or early May.