LONDON—After clinching the year-end world No. 1 ranking for a third time, Rafael Nadal admits that pulling off the feat became important to him as the season progressed, even though he said on numerous occasions that it was not critical, including before the ATP World Tour Finals.

“Today was more important [to] secure the No. 1 at the end of the season,” he said. “That's the real thing. Because at the end during all my season I said is not my goal, but the real thing is after all the success I had during the season, winning, five Masters 1000s, playing a final in another, winning a few 500s, playing another final, winning two Grand Slams, so I think that after all what happened last year, I felt I deserved to be there at the end of the season. And today I did. So was one of the best things that I did in my career: Come back to the No. 1 after three seasons. That's very difficult in our sport, and after a very important injury. That's an emotional thing for me, for sure.”

Nadal added the goal became important to him after he beat Novak Djokovic to win his second U.S. Open title. He then lost in the final of Beijing to Djokovic, lost in the semifinals of Shanghai to Juan Martin del Potro, and the semifinals of Paris to David Ferrer. He has won his first two matches in London.

“I felt that I had everything to be there," Nadal said of his feeling after he left New York. “But at the same time, I have a zero in Australia, I have a zero in Miami, I have a zero in Wimbledon. A lot of zeros to be No. 1. I think is a great effort because I have unbelievable competitors in front. That makes the year‑end No. 1 very, very special. You can feel how tough is everything that winning all the things that I win this year, until the last tournament, I was not able to make it. So that makes everybody think how difficult [it] is be there.”

Nadal said his goal for next year will not be to fight for No. 1, but to be fit for the Australian Open (which he missed the first month of the season last year) and be prepared for the biggest tournaments.