It was the most magical moment of a 125-120 win over the Thunder on the Knicks’ most magical day of the season. Raymond Felton drove down the lane, was met by the Thunder’s big bodies, stopped and lost his balance. As he fell, Felton lost control of the ball as the Knicks were losing control of the game.

Somehow, Felton batted it out to an unsuspecting J.R. Smith, standing behind the 3-point line. A surprised Smith collected it, and with the shot clock ticking down, fired in a 26-footer with 56.8 seconds left, lifting the Knicks into a 120-113 lead and ending Oklahoma City’s hopes.

“It was kind of crazy,’’ said Smith, who finished with 22 points. “I thought Raymond was going to get the layup. I started backwards toward halfcourt. He kicked it back. Looking at the shot clock, it was going down and I tried to get it as high as I could. My shot was kind of short all day. Fortunately it went in.’’

It was that kind of afternoon.

“It was just a freak accident, a great play. I just fell down and tried to get it back to him,’’ Felton said. “He did the rest.’’

A month ago, Smith had a chance to beat Oklahoma City at the Garden, but his buzzer-beater from the corner missed in a one-point loss. Smith was criticized for not driving the ball. Since then he has been a driving machine.

“That was a shot I normally make,’’ Smith said.