New Delhi, Nov. 3 -- Zverev won the French Open and the U.S. Open, putting to rest his tag as the best player yet to win a Grand Slam. He's guaranteed the year-end No. 1 ranking, too.

"It's a very special day, for sure," Zverev said in Paris, where he is set to compete in the Paris Masters this week.

"Paris has been quite special to me this year, generally. It's a place where I had a lot of up-and-downs, I had a lot of heartbreak, but this year, winning my first Grand Slam here and becoming world No. 1, it's a very special feeling."

He became the 30th man to reach No. 1, and the oldest in more than 50 years to top the rankings for the first time. John Newcombe was 30 when he reached the top spot in 1974.

Zverev reached the rankings su...