Nadal clinches year-end world No. 1 ranking

PARIS -- In a remarkable year for men's tennis, Rafael Nadal has defied expectations and guaranteed he will end 2017 as the world No. 1.

The 31-year-old Spaniard sealed the year-end crown Wednesday with a hard-fought 7-5, 6-3 victory at the Paris Masters against rising South Korean star Hyeon Chung.

In front of a close-to-capacity crowd at the AccorHotels Arena, Nadal looked frustrated at times. He made more errors than usual and was forced to move around the court by his opponent -- one of the ATP's highly rated "Next Generation" players -- in a match that lasted close to two hours.

If Chung had been considered a footnote, he hadn't been notified, and the celebrations of the 16-time Grand Slam champion after the match spoke of how hard Nadal had to work in his opening match in Bercy.

Roger Federer's late withdrawal from this tournament, to rest for the ATP Finals in London later this month, made Nadal an overwhelming title favorite before the Paris Masters began. Still, the latest statistical marks that accompany Nadal's accomplishment highlight the skill he has shown throughout his storied career.

Nadal's victory means he has claimed the record as the oldest year-end No. 1, the first No. 1 older than 30 since the ATP rankings were established in 1973.

He also became one of only four players -- joining Ivan Lendl, Federer and Novak Djokovic -- to have regained the year-end top ranking after losing it, having also finished 2008, 2010 and 2013 as the world No. 1.

"Of course it was not the goal," Nadal said about being number one at the end of the year. "It was impossible for me to think about that when you are coming back from a tough period of time without playing tennis and with so many injuries in last couple of years."

WATCH: Four-time year-end world No. 1 Rafael Nadal reveals the secret to his success.

Leo Spall, UK Correspondent413d ago

Nadal had to pull out of the French Open and missed Wimbledon last year because of a wrist injury. He's also missed several months in recent years due to knee injuries including this season.

Nadal now looks to move on and win the Paris Masters for a first time.

Many had hoped the pair would duel for the ATP Finals title and the year-end No. 1 ranking (which Federer hasn't captured since 2009) at the O2 Arena to close out the ATP season, much like Djokovic and Andy Murray did a year ago.

Nadal, who has never won the ATP Finals, has maintained through most of the year that the year-end title was not a target, yet he has worked hard to earn it.

Among the six titles he has added to his collection this season are two majors: the French Open and US Open, the latter of which he won after climbing to the top of the rankings once again.

Nadal will next play Pablo Cuevas at the Paris Masters.