Undisputed heavyweight champion Oleksandr Usyk doesn’t have much left to prove.

After beating Tyson Fury, Anthony Joshua and Daniel Dubois twice each over his last six fights spanning four years, Usyk (24-0, 15 KOs) is alone at the mountaintop, waiting to make his next move.

Conversations around the sport are calling for the 38-year-old Ukrainian to retire, while others are suggesting Joseph Parker and Moises Itauma should get a crack.

Boxing icon and former undisputed heavyweight champion Lennox Lewis says Usyk should march to the beat of his own drum.

“I would say to him to retire at your own time, but retire on top like I did," Lewis told Sky Sports. "When a guy retires, it's really down to him. He's got to feel that push that he wants to retire. But he can teach a lot of young boxers a lot of different things — dedication, hard work, sacrifice — because he's been through that.

"It's definitely the hardest thing to do because you basically want to be the best in boxing and take all the belts for yourself and be the number one guy.

"There's always other boxers out there that don't want you to achieve that. They're standing by, they want to beat you, they want to be the first boxer to beat you. That's why you've got to make sure that you retire on top."

Lewis retired at 38 after stopping Vitali Klitschko on a cut in 2003. A knockout win against Mike Tyson preceded that performance in 2002, and Lewis avenged a knockout loss to Hasim Rahman by returning the favor in 2001. Lewis (42-2-1) beat Evander Holyfield, David Tua, Andrew Golota and Shannon Briggs along the way.

As for Usyk, he’s been nursing a back injury ever since knocking out Dubois in July and is also starring in “The Smashing Machine” opposite Dwayne "The Rock" Johnson.