Cooper Flagg made his NBA Summer League debut Thursday night and although he and the Dallas Mavericks earned the win, the No. 1 NBA Draft pick called it “one of the worst game of my life.”

LAS VEGAS (AP) — Cooper Flagg strolled into UNLV’s Thomas and Mack Center at 4:17 p.m. on Thursday, wearing Dallas Mavericks gear, bright white New Balance shoes, and an emotionless look on his face as he passed through security.

Flagg’s first points as a pro came on a slam dunk with less than five minutes to go in the first quarter. The Mavericks guard finished with 10 points, six rebounds and eight assists in his debut. He played 32 minutes, making 5 of 21 field goals, missing all five of his three-point attempts.