Rafael Nadal has gone through a lot since his last reign at World No. 1, on June 6, 2014.

Yet, more than three years later, he is set to regain the illustrious spot at the top of the tennis mountain.

During that time, he has experienced a lot of injuries, and many early round upsets in numerous failed Grand Slam attempts.

Yet, this calendar year has seen Nadal back to his best, having claimed a record 10th Roland Garros title, and achieved a total of four titles.

Nadal and Federer were set to battle for the top Emirates ATP ranking this week at the Western & Southern Open in Cincinnati.

But, with Federer's withdrawal because of a back injury on Monday, Nadal is guaranteed to take the top spot in one week.

“Obviously it's bad news for the event that Roger is not playing. For me personally obviously to be back to that position is something special,” Nadal said on Monday during his pre-tournament press conference.

“A lot of things have happened since the last time I was in this spot. Injuries and some tough moments, of course, but I have held the passion and the love for the game, and that's why I have the chance to be back in that position again.

"So I'm just trying to enjoy the moment and just trying to be ready to compete well here. That's the most important thing for me now."

With the US Open coming up next month, new world No.1 Nadal will surely be considered the favourite.

His main challengers Andy Murray, Roger Federer, and Novak Djokovic all have injuries and are all in some doubt to compete at Flushing Meadows.

With his recent French Open victory, Nadal has won the second most Grand Slam titles, only behind Roger Federer.

Now that he has returned to the peak of his performance, Nadal can concentrate on chasing down Roger Federer and become No.1, not only in the world, but in Grand Slam titles of all time.