PARIS - Rafael Nadal continued a remarkable season by ensuring that he will end the year as the world number one for the first time since 2013, completing a long road back to the top of the sport.
The 16-time Grand Slam champion beat South Korean Hyeon Chung in his second-round match at the Paris Masters to open an unassailable lead over Roger Federer in the race to finish the year at the top of the rankings.
Nadal, 31, has now ended four years as the world's best player, having first achieved the feat in 2008 when he won his maiden Wimbledon title with an epic victory over Federer.
He is the oldest player to end a season as number one and the first over the age of 30, despite starting 2017 ranked ninth after two years plagued by problems with form and fitness. But he dug deep, using his renowned work ethic to rediscover his very best form.
"It's about the passion for what you are doing," Nadal said. "It's about the mentality of waking up every morning with the right motivation to go on court and improve something. Everybody wants to win when we are competing and when we are on the tennis court.
"Another thing is (to) wake up every morning with the passion to go on court and with the passion to improve something and practice every day with the right attitude to try to make that happen. So that's another story, no? Not everybody is able to do it."
When Nadal reclaimed the world number one ranking in August, it was the first time in more than three years he had topped the list.
And when Federer withdrew from the final event of the regular season in the French capital, Nadal knew he needed to win just one match to be certain of ending 2017 at the summit.
Nadal overcomes bumps in the road
It has been a long and topsy-turvy journey for Nadal to his latest brilliant season, which delivered a 10th French Open crown at Roland Garros before victory at the US Open moved him to three shy of Federer's all-time record of 19 Slam singles titles.
Nadal - who was coached by his uncle Toni from childhood until after his Flushing Meadows win earlier this year - won an under-12 regional crown at age eight and by 12 had captured Spanish and European age-group junior titles, before turning professional at 15.
Nadal won his first match against Federer just two years later. As a 19-year-old, he won the 2005 French Open on his debut, the start of a legacy that would cement him as the greatest player ever seen on clay. It was early in his career when Nadal began his habit of biting the championship trophies he wins.
He added Wimbledon crowns in 2008 and 2010, an Australian Open title in 2009 and completed the career Grand Slam in 2010 by defeating Novak Djokovic in the US Open final, becoming the youngest man in the Open era to complete the sweep.
Only Nadal and Andre Agassi can say they have a career Grand Slam and an Olympic men's singles gold medal, Nadal claiming his in 2008 at Beijing. Nadal added another US Open crown in 2013, again downing Djokovic in the final.
Knee injuries took a toll throughout his career, costing him nine Slam appearances, and after he failed to even reach a major semi-final in 2015 and 2016 many figured his greatest moments were behind him.
But Nadal roared into January's Australian Open final, losing to Federer, then captured his record 10th French Open title in June, setting the stage for another major victory in New York three months later.
He returned to Paris on Wednesday to become only the seventh man to finish as the year-end number one on four or more occasions. Now Nadal is looking for a maiden title at Bercy, which would take him clear of Serbia's Djokovic with a record 31st Masters triumph.