Nadal won his 33rd ATP World Tour Masters 1000 title on Sunday when he beat Stefanos Tsitsipas at the Rogers Cup.
It was the 80th title of his career and the 50th at either Masters 1000 level, at the Grand Slams or ATP Finals.
Nadal is yet to win at the end of season ATP Finals despite eight appearances.
Federer tops the list with 20 Grand Slams, six ATP Finals wins and 27 Masters 1000 titles.
Wimbledon champion Novak Djokovic is third with 13 Grand Slams, five ATP Finals wins and 30 Masters 1000 titles.
Federer and Djokovic can add to their list if they are successful at this week’s Cincinnati Masters.
Nadal withdrew from the event hours after winning the Rogers Cup citing the need for rest.
He wrote on Twitter: “I am very sorry to announce that I won’t be playing in Cincinnati this year.
“No other reason than personally taking care of my body and trying to keep as healthy as I feel now.
“I am very thankful to my friend Andre Silva, tournament director of the Cincinnati tournament, who after speaking to him on the phone understood what I said and understands the situation.
“I am sure the tournament will be a success and I wish him and his team all the best. I am also sad for those amazing fans in Cincy and around who always gave me great support.
“I am sure I’ll see them next year and I am sorry I won’t be with them this year. Thanks for all the support as always.”
Speaking after winning the Rogers Cup, Nadal expressed his delight at claiming another Masters 1000 title.
“It’s great news. It’s a tournament that I won four times,” said Nadal.
“Canada is a place that I feel comfortable. I play well. That’s it. And I played with the Canadian colors during the whole event.
“My 80th tournament is of course great number, an important one. I’m very happy, but it’s about another Masters 1000.
“Masters 1000s are tournaments [that are] so difficult to win, sometimes [they] are even more difficult to win than Grand Slams, because you can’t avoid tough opponents.”