Gray threw 35 pitches Friday in a bullpen session at Fenway Park, all fastballs, Bobby Blanco of MASNSports.com reports.

EDGE Analysis

The right-hander has been sidelined since April 4 due to a flexor strain in his elbow. Gray is slowly building up in bullpen sessions, and the Nationals haven't indicated yet when he might begin a rehab assignment, but he'll need to start ramping things up quickly if he's going to return to the big-league rotation before the end of May.