Rafael Nadal of Spain serves during the second round match against Chung Hyeon of South Korea at the ATP World Tour Masters 1000 Indoor tennis tournament in Paris, France, Nov 1, 2017. Rafael Nadal won by 2-0. [Photo/Xinhua]

PARIS - Spanish tennis ace Rafael Nadal secured a year-end top position in the ATP Rankings following his victory over South Korean talent Chung Hyeon in the second round of the Paris Masters on Wednesday, while promising German star Alexander Zverev was turned down by Robin Haase in full sets.

Nadal, 31, has become the oldest year-end No 1 and first year-end No 1 over the age of 30 since the ATP Rankings were established in 1973.

This is his fourth time to be crowned world No 1 at the end of the season, after 2008, 2010 and 2013.

"I'm very, very happy for everything," Nadal told crowds in an on-court interview. "It has been an amazing year. One year ago, for sure I never dreamed about being world No 1 again at the end of the season. It's something that means a lot to me."

Nadal emphasized that "the season is not over."

"Here in Paris, the most important city in my career without doubt, I'm just looking forward to getting to the point," he said.

After both sides held their serves in the first two games, Chung broke for the first time throughout the match, before Nadal made a strong comeback to nail four games in a row.

Chung showed his resistance and tied it at 5-all. Then Nadal regrouped himself and took away the first set at 7-5 with a big forehand.

The second set was in balance after seven games, before Nadal, in search for his career 31st ATP Masters 1000 titles, made a crucial break in the eighth game, and converted his second match point in the ninth at 6-3.

Nadal will next face Pablo Cuevas, as the Uruguayan saw off Nadal's compatriot Albert Ramos-Vinolas 6-7 (5), 7-6 (1), 6-2.

"Tomorrow there will be a tough opponent. Pablo is always a tough one. I need to play well, but as I say, I hope to be ready to make that happen," remarked Nadal.

Zverev, who has won two ATP Masters 1000 titles this season as Nadal did, recorded a comfortable 6-3 win in the first set. However, the 20-year-old German failed to prevent his Dutch opponent from winning 78 percent on service points, and the match turned around at 6-2, 6-2 at the expense of Zverev, who will prepare for his maiden appearance at November's ATP Finals in London.

Marin Cilic and Grigor Dimitrov, who also secured their places in ATP Finals, both came through their opening matches in Paris.

Juan Martin del Potro, the No 13 seed, continued his hopes of catching up with the ATP Finals with a 6-2, 6-2 victory over Joao Sousa, joined by David Goffin and Lucas Pouille in Thursday's round of 16.

But it was a disappointing day for South Africa's Kevin Anderson and home favorite Jo-Wilfried Tsonga, as the two contenders for ATP Finals berths were knocked out from the tournament.