Allen Iverson Doles Out NBA Advice To Cooper Flagg

Allen Iverson is offering up NBA advice to Cooper Flagg ... and as a former No. 1 overall pick who went on to become a Hall of Famer -- the Dallas Mavericks star sure would be wise to listen up!!

The Answer doled out several tips to this year's top draft selection while chatting with TMZ Sports just before Flagg's Wednesday night debut.

Iverson's first bit of guidance was straightforward ... as he implored Flagg to take things "one day at a time."

Then, the former point guard -- who just premiered his new docuseries "ALLEN IV3RSON" in NYC -- told Flagg effort is the biggest thing to take care of when he hits professional hardwoods.

"The most important thing, and I think this will take care of everything, is playing every game like it's your last, you know?" Iverson said. "You do that and everything else takes care of itself."

Flagg would certainly be smart to heed the talk -- especially after his opening night in the Association didn't go quite as planned.

Flagg scored just 10 points on 4-of-13 shooting ... and Dallas got blown out, 125-92.

But the 18-year-old's got a few more hours to digest Iverson's words and turn things around in time for game No. 2 -- which tips off against the Wizards later Friday night.

For the diehard hoopheads, check out the rest of the clip -- AI gave his take on the Philadelphia 76ers as the season gets underway, as well as Joel Embiid's minute plan.