These old Mets alternate jerseys are returning

The Mets will be back in black — Fridays at Citi Field.

A day after owner Steve Cohen, in a YouTube chat, said the team’s alternate black jerseys would return in some capacity this season, Pete Alonso on Tuesday let slip with the organization’s plan.

“Friday night blacks at home, that is going to be fun,” Alonso said. “So mark it in your calendars.”

The team first began wearing the alternate black jerseys in the 1990s but discontinued them in recent seasons.

Alonso was asked about the clubhouse reaction to the black jerseys returning.

“Everyone was like, ‘Let’s f—ing go,’ ” Alonso said. “It was awesome. Everybody is fired up and I hope Mets fans are fired up, too. It’s going to be special.”

Too much Jacob deGrom on normal rest can’t be a bad thing.

The Mets ace is scheduled to pitch Thursday night’s opener in Washington and return five days later, skipping ahead of the No. 5 spot in the rotation, according to the alignment announced by manager Luis Rojas.

Rojas had the option of pitching deGrom on the sixth day because Friday is blank on the schedule, following the opener.

It will leave the Mets with an alignment of deGrom, Marcus Stroman and David Peterson for the opening series in Washington. The ensuing series in Philadelphia is scheduled to open with Taijuan Walker starting for the Mets, followed by deGrom then likely Joey Lucchesi (or an opener pitching ahead of the left-hander). Stroman would pitch the Mets’ home opener a week from Thursday.

The caveat is the weather. With rain in Thursday’s forecast in Washington and nighttime temperatures predicted to plunge into the low 30s, a postponement could loom that would push deGrom’s ensuing start to next Wednesday in Philadelphia.

DeGrom will be starting his third Opening Day for the Mets, putting him on a list with Tom Seaver, Dwight Gooden and Johan Santana among pitchers in franchise history to start three straight openers.

Peterson threw live batting practice, facing Jonathan Villar, Jeff McNeil, Tomas Nido and Albert Almora Jr. over two innings at Nationals Park.

The Mets’ taxi squad for the opening series: Steven Tarpley, Trevor Hildenberger, Jose Peraza, Mallex Smith and Caleb Joseph.

— Additional reporting by Ken Davidoff