TIME WILL TELL TMZSports.com
It's time to start buying into the Cooper Flagg hype if ya haven't already ... 'cause NBA star Jaime Jaquez Jr. tells TMZ Sports that after playing with the phenom this summer, he's the real deal.
Flagg -- the No. 1-ranked H.S. player in the nation in the 2024 class -- and Jaquez Jr. teamed up to help prep America's men's national squad for the Olympics in early July ... and Flagg put on a show.
According to those in the Las Vegas gym at the time, he dazzled as he repeatedly got buckets against LeBron James, Steph Curry and the rest of Team USA's roster.