NEW YORK — The already shorthanded Mets saw their playoff chances dealt another blow when left-hander Steven Matz was scratched from his scheduled start Friday because of shoulder soreness.

Matz, 9-8 with a 3.40 ERA, hasn't pitched since Aug. 14 because of tightness in his shoulder but threw a bullpen session Wednesday and was set to return.

General manager Sandy Alderson said the rookie's shoulder again felt sore one day after the bullpen session.

“We'll see where this takes us,” Alderson said. “But for the next several days, that shoulder issue has to resolve itself before we consider pitching him again.”

Right-hander Gabriel Ynoa will instead make his second major league start.

The Mets already are missing pitchers Matt Harvey, Jacob deGrom, third baseman David Wright and second baseman Neil Walker.

Noah Syndergaard is pitching with a bone spur in his pitching elbow, while Asdrubal Cabrera and Yoenis Cespedes are playing with lingering injuries.

“I'm feeling some symptoms,” Matz said. “At this point, I don't have an answer. I know the difference between soreness and pain. … This is a little different than regular soreness.”

Manager Terry Collins said it would be difficult to select Matz for a playoff start.

“It would be hard to get him enough innings that you could consider starting him in the postseason,” Collins said. “We'll just have to wait to see what the next few days have in store. When you're talking about the shoulder, you're talking about serious territory, so it's got to really calm down before we'd consider getting him back out there.”