The Knicks are not just beating the Celtics, they’re in their heads

Let’s just save everyone in two cities some time on Saturday afternoon.

Skip the first half of Game 3 of the NBA’s Eastern Conference semifinals, spot the Celtics a 20-point lead, put 16 minutes on the clock and see how long it takes the Knicks to stage an epic comeback.

Yogi Berra once said, “Baseball is 90 percent mental. The other half is physical.”

Well, after a second straight 20-point road rally to victory by the Knicks, this second-round playoff series now is 100 percent mental, and the Celtics’ physical advantage — superior talent — is meaningless.