Cooper Flagg made his highly anticipated debut for the Dallas Mavericks in a preseason game against the OKC Thunder on Monday. Dallas coach Jason Kidd named the No. 1 pick as one of the starters, with the Duke phenom joining Anthony Davis, Klay Thompson, D'Angelo Russell and Dereck Lively II in the lineup.The 6-foot-9 rising star wasted no time in getting the crowd inside Dickies Arena on their feet. Cheers and applause erupted when Flagg showcased his athleticism and used his size to pull off an incredible block, which sparked a fast break for the Mavericks and led to an Anthony Davis dunk.Flagg didn’t open his account in the scoring column in the first quarter but demonstrated that he can impact the game in multiple ways. The Mavericks rookie had zero points on 0 of 2 shooting, including 0 of 1 from 3-point range, after playing 6:36 minutes in the opening period. He also recorded three rebounds, two assists and one block.The Mavericks rookie found his offensive rhythm and 3-point stroke in the second quarter. After missing his two field-goal attempts in the opening period, Flagg stayed aggressive and continued to shoot with confidence. He attempted four shots in the second quarter, two from inside the arc and two from beyond it.He missed one of his two 2-point attempts but made both of his 3-pointers, once again showcasing how tough of a defensive assignment he’s going to be for opposing teams. Another standout aspect of his performance on Monday was how well he complemented Anthony Davis on defense and on the boards.At half time, Cooper Flagg had 10 points on 3 of 6 shooting, including 2 of 3 from 3-point range, and 2 of 2 from the free-throw line. He also recorded six rebounds, three assists and one blocks in 14 minutes.Insider puts NBA on notice ahead of Cooper Flagg's rookie season Senior NBA insider Marc Spears made a blunt statement ahead of Cooper Flagg's preseason debut for the Dallas Mavericks on Monday. Speaking on ESPN’s NBA Today, Spears criticized the media for not giving the Mavericks rookie enough hype and emphasized why Flagg is destined for superstardom. "Nobody's talking about this guy and they're making a mistake," Spears said. Before making his NBA preseason debut for Dallas, Flagg appeared in two Summer League games after being drafted earlier this year. He averaged over 20 points across both contests and showcased his all-around skill set by filling up the stat sheet in every category.