On Saturday night at the U.S. Open, the tennis world finally will get the tantalizing matchup its been begging for: Naomi Osaka vs. Coco Gauff. The sport’s top player against it’s not-too-distant future.

They will face off for the first time under the lights Saturday night at Arthur Ashe Stadium, the defending champion and world No. 1 trying to fend off Gauff, and the 15-year-old American phenom trying to keep Cocomania going. Must-see viewing is an understatement.

“Obviously she’s an amazing player. She’s defending champion, she’s won two Slams, she’s No. 1, she’s only 21,” Gauff said. “We’re both pretty young, but I’m a little newer to the game, so I’m just curious to see how my game matches up. Obviously I want to win. I just want to enjoy it, have fun, enjoy the battle.”

Gauff’s love of the battle — shown in her run to the fourth round of Wimbledon that put her on the world stage — has impressed.

“Off the court she seems like me,” Osaka said, adding with a laugh, Well, she seems a little bit more like she knows what she’s doing. I’m very quiet.”

Knows what she’s doing is an understatement. Gauff is the youngest American woman in the Round of 32 at the U.S. Open since Jennifer Capriati in 1991, the youngest woman period since Anna Kournikova in 1996.

“She’s had the mindset since very young that pressure is a privilege,” Gauff’s mother Candi told The Post. “Are you going to bust like a pipe or are you going to shine like a diamond? This is something that’s been ingrained.”

Gauff said her parents never put pressure on her, but they clearly taught her how to handle it.

“If nobody’s expecting you to do anything, then that means you don’t have anything to give. If they expect something, that means you’ve got something to give,” Gauff’s father Corey told The Post. “Pressure comes with sports. I tell her if you’re scared, don’t go out there.”

The pressure will be off Gauff and shifted to Osaka. In the entire Open era, no woman in her debut at a major has beaten a player who was both the defending champ and top seed. That’s 0-for-67. Still, Gauff says she actually feels less pressure as a pro than as a junior.

“Since I was ranked pretty high, I felt pressure to always do well,” Gauff said. “And now in the pros, I’m enjoying it a lot more. … Now

I’m really enjoying it more and I’m the underdog in a lot of the matches and I’m just out there having fun.”

With Gauff ranked 140th despite all the recent hype, all the expectations will be on Osaka. Even John McEnroe said on ESPN it would be bad for tennis for such a young player to beat the champ.

“The pressure is going to be more on Naomi. Coco, the last two matches, I don’t know why, but she was expected to win. She walked on the court with expectations that she’s going to win,” Corey Gauff said. “This will be one of the few times she’ll go on the court as underdog. She can play freely and relax.”

Though Osaka and Gauff have never faced each other, they have been friendly for years. They hit together a couple of years ago before the Miami Open, while their dads are close and speak often.

“I saw her [Gauff] in the locker room. She wasn’t really talking to anyone. I was like, ‘Oh looks familiar. I’m going to talk to her.’ She’s super young, and I know it’s hard to transition,” Osaka said.

“I can only imagine as a junior you play these tournaments with your friends, and then you come to the pros and you don’t know anyone. … She’s super sweet and I’d love to play her. When I hear people talking about someone, I want to have the opportunity to play them just to assess it for myself.”