Edwin Diaz threw a bullpen session before the Mets’ 3-2 loss to the Nationals, adding sliders to his workout for the first time in his rehab from right patellar tendon surgery, according to manager Buck Showalter, who was among the team personnel who watched the session.

Showalter said Diaz’s fastball is within “three or four clicks” of normal range, which he indicated equated to the 95-mph neighborhood.

The Mets haven’t ruled out the possibility of Diaz, who began traveling with the team this week, returning this season.

Luis Guillorme is scheduled to play in a minor league rehab game on Friday for Single-A Brooklyn.

The infielder has been on the injured list since July 22 with a right calf strain.

DJ Stewart was on the bench for a second straight game with lower back soreness, but Showalter said the outfielder should be ready for a return to the lineup on Friday at Minnesota.

Brandon Nimmo has 22 homers this season from the leadoff spot, tied for third in franchise history.

Curtis Granderson set the Mets’ record with 26 homers from the leadoff spot in 2015.

Tommy Agee hit 24 homers from the leadoff spot in 1970 and 22 in that position in 1969.

Nimmo had his second two-homer game of the year on Tuesday to extend his career-high in homers for a season.