Antetokounmpo finished with 34 points, 17 rebounds and six assists in a dominant display to guide the Milwaukee Bucks to a 120-108 road win over the Pelicans.
Williamson had his moments - an aggressive grab to take a rebound away from Antetokounmpo in the fourth quarter arguably the highlight - but was very much second best to the Bucks superstar.
The 19-year-old, who managed 20 points, seven rebounds and five assists, said: "I mean, he's a former MVP.
"It's like going up against any great player. Do as much as you can to slow him down.
"He's his own player; he brings his own style to the game. That's why he's Giannis."
Statistically, it was the worst night of Williamson's fledgling NBA career - he shot just 5-of-19 from the floor - with Antetokounmpo admitting the Bucks' defense had paid him special attention.
He said: "I think we put a lot of guys, a lot of different looks to him.
"I was guarding him, Brook [Lopez] was guarding him, Robin [Lopez] was guarding him, Pat [Connaughton] was guarding him. Just tried to make him guess, just tried to make it as tough as possible.
"You know he's gonna try to go left, try to overpower whoever's guarding him, try to go and finish strong. And the guys behind gotta be active, gotta make it as tough as possible."
Despite his struggles, however, Antetokounmpo also saw enough to suggest Williamson was a star in the making, adding: "He'll be a really good player for a lot of years to come.
"He's out there helping the team; he's competing as hard as possible. He's just gotta stay healthy, and he's gonna have a bright future."