"To regain the No. 1 ranking nine years after having first reached it is unprecedented," ATP president Kermode said in a statement.
"Rafa has been setting records throughout his remarkable career and this one is as impressive as any. It shows incredible dedication and longevity, and we congratulate him on this amazing achievement."
Nadal, a 15-times grand slam winner, came back from a series of knee and wrist injuries to reach the Australian Open final and claimed a record 10th French Open title this season.
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"Being No. 1 after all the things that I have been going through the last couple of years is something unbelievable, so (it) is, for me, an amazing achievement to be back to that position after three years," said Nadal.
Nadal has claimed four titles on tour this season, winning 49 matches and losing nine in a stellar 2017.
(Reporting by Hardik Vyas in Bengaluru; editing by Sudipto Ganguly)
