Jalen Brunson sank the game-winning 3-pointer with 6.2 seconds left Friday night for the host New York Knicks, who squandered all of a 21-point lead before edging the Brooklyn Nets 124-122 in NBA Cup Group A action

Dennis Schroder’s 3-pointer with 12 seconds remaining gave the Nets their first lead since the first quarter. Following a timeout, Brunson took an in-bounds pass from Mikal Bridges and sized up Dorian Finney-Smith before hoisting a shot that got nothing but net.

The Nets, who were out of timeouts, raced up the court, but Schroder’s layup was blocked by Bridges and Ariel Hukporti cradled the rebound as time expired.

Brunson — who missed the potential game-winning shot at the buzzer in Wednesday’s 124-123 loss to the Chicago Bulls — finished with 37 points Friday as the Knicks improved to 2-0 in Group A play. OG Anunoby had 25 points and eight rebounds before fouling out with 4:15 left and New York up 114-108.

Josh Hart (14 points, nine rebounds, nine assists) just missed a triple-double while Bridges had 22 points in his first game against the Nets since he was dealt by Brooklyn to the Knicks in July. Cameron Payne added 10 points off the bench.

Cam Thomas scored 12 of his 43 points in the fourth quarter for the Nets, who outscored the Knicks 40-24 in the final 12 minutes before dropping their Group A opener. Cameron Johnson had 10 of his 17 points in the fourth while Finney-Smith (15 points) and Schroder (14 points) also got into double figures.

The Knicks outscored the Nets 32-23 in the third, when they took their biggest lead at 98-77 on Bridges’ 3-pointer with 1:17 left.

New York led 100-82 entering the fourth, but Brooklyn cut the deficit to single digits for good with 6:45 remaining and got within one possession twice before Schroder’s second-chance 3-pointer set up Brunson’s dramatic shot.