This article lists the professional tennis players who reached the highest ranking among their compatriots during the Open Era.
On 11 September 2017, Garbiñe Muguruza and Rafael Nadal made Spain the first country since the United States 14 years ago to simultaneously top both the ATP and the WTA rankings, with Muguruza making her debut in the No.
The most recent previous such pair were Serena Williams and Andre Agassi, 28 April to 11 May 2003.
[1] * Goran Ivanišević is included for both Yugoslavia and Croatia, and Novak Djokovic is included for both Serbia and Montenegro, and Serbia.
* Monica Seles is included for both United States and Yugoslavia.