The world No. 1 talked about his eventual retirement, mentality, longevity and more. (Getty Images)

As foreshadowed in a Sports Illustrated story, Rafael Nadal spoke with Jon Wertheim on 60 Minutes on Sunday night about a range of topics, including his longevity in the sport and his champion's mentality that involves turning doubts into powers.

The interview sessions took place in tennis' blink-and-it's-gone offseason, on Nadal's beloved home island in Spain. Wertheim is a 15-year veteran of covering the Bull from Mallorca, and poked fun at himself in the conversation for, four years ago, opining that the tennis world was certainly seeing in Nadal an athlete in "decline."

Fast-forward to 2020: Nadal will soon star as the No. 1 seed in men's singles in the Australian Open, though coming off a straight-sets loss to Novak Djokovic in the ATP Cup's team championship round. (It was another scorcher between the two at its conclusion.)

Still, he has momentum, having won the most recent major event, also on hard courts, at the US Open. As Wertheim rightly noted, the King of Clay actually has as many major titles on the crushed brick surface as Hall of Famers John McEnroe and Venus Williams have in total.

The US Open was Nadal's remarkable 19th Grand Slam singles title, igniting speculation about what his overall haul will be, as he's now one crown behind his rival and the current, nearly inarguable GOAT: Roger Federer.

In the 60 Minutes piece, Nadal reflected in his native Spanish on how he proverbially eats doubts for breakfast: "If you don't have doubt, it probably means that you're being arrogant. [Doubt] is good for me, because then I feel alert. Tennis is a sport where things can change very quickly. That's the great beauty of our sport."

Perspectives like that separate legends from journeymen. Nadal's status to that end is already secure, but where he ultimately lands isn't yet set.