Spain's Rafael Nadal remained in the number one spot in the men's Association of Tennis Professionals (ATP) world singles rankings released on Monday with 8,770 points while Bulgaria's Grigor Dimitrov jumped to the fourth spot.

Nadal kept his place atop the rankings after winning the Barcelona Open, defeating Greece's Stefanos Tsitsipas in straight sets, reports Efe.

Switzerland's Roger Federer stayed in second place, ahead of Alexander Zverev in third, after the German won the Bavarian International Open against his compatriot Philip Kohlschrieber.

The Swiss legend has chosen to skip the clay court season in order to fully prepare for the grass court season following the French Open, which ends on June 10.

After losing to Tunisia's Malek Jaziri 6-4, 6-2 in the Istanbul Open round of 16 last week, Croatia's Marin Cilic fell to fifth place.

Meanwhile, Portugal's Joao Sousa rocketed 20 places up to 48th, following his 6-4, 6-4 victory over the United States' Frances Tiafoe at the Estoril Open final on Sunday.

The current top-10 ATP rankings and point scores are as follows:

1. Rafael Nadal (Spain) 8,770 Points
2. Roger Federer (Switzerland) 8,670
3. Alexander Zverev (Germany) 5,195
4. Grigor Dimitrov (Bulgaria) 4,950
5. Marin Cilic (Croatia) 4,780
6. Juan Martín del Potro (Argentina) 4,470
7. Dominic Thiem (Austria) 3,545
8. Kevin Anderson (South Africa) 3,345
9. John Isner (US) 3,125
10. David Goffin (Belgium) 3,020.