Novak Djokovic has started his 421st week at No 1 in the ATP Rankings, but the tennis great has already secured up his next rankings milestone after reaching the semi-final of the Monte Carlo Masters.

Despite suffering a shock last-four defeat at the hands of Casper Ruud at the ATP Masters 1000 event, Djokovic’s run means he is assured of staying at the top of the rankings for another month.

The 24-time Grand Slam winner is now set to remain at No 1 until at least May 20, which will put him on an astonishing 425 weeks at the top. His biggest rivals for the No 1 ranking failed to chip away at his lead as the 36-year-old has increased his advantage to 1,285 points over Jannik Sinner with Carlos Alcaraz another 105 points adrift in third place.

And the gap between the top three will get slightly bigger this week as the trio won’t be in action with the top two skipping action while Alcaraz is unable to defend his Barcelona Open title due to concerns over his forearm. Djokovic will only drop 40 points, Sinner will drop 90 points and Alcaraz will drop 500 points.

There were a couple of big changes in the top 10 as Casper Ruud moved up four places to No 6 after finishing runner-up in Monte Carlo while Stefanos Tsitsipas is up five places to No 7 following his title run. Holger Rune was the big loser as he dropped five places to No 12 after exiting in the quarter-final.

Just behind the Dane is Ben Shelton with the 21-year-old confirmed as the new American No 1 for the first time in his career as the result came on the back of his title run at the US Men’s Clay Court Championships last week and Taylor Fritz’s Monte Carlo nightmare.

Fritz’s first-round exit saw him drop two places to No 15 while Ugo Humbert jumped to sports to a career-high No 13. Further down the list, Sumit Nagal was a big mover as he jumped 13 places to a career-high No 80 after becoming the first Indian male player to win a Masters 1000 match on clay. He came through qualifying in Monte Carlo and beat Matteo Arnaldi in three sets in the first round before losing to Holger Rune.

Australian Thanasi Kokkinakis jumped 12 places to No 94.

Meanwhile, former world No 6 Matteo Berrettini has dropped 14 places and now finds himself close to exiting to top 100 as he sits at No 98. The good news for the Italian is that he doesn’t have any points to defend over the next two months as he was out injured last year.

Three-time Grand Slam winner Stan Wawrinka is 12 places above Berrettini as he dropped seven places after his first-round exit.

ATP Rankings Top 20 1. Novak Djokovic, Serbia – 10,035 points 2. Jannik Sinner, Italy – 8,750 3. Carlos Alcaraz, Spain – 8,645 4. Daniil Medvedev – 7,085 5. Alexander Zverev Germany – 5,425 6. Casper Ruud, Norway – 4,025 7. Stefanos Tsitsipas, Greece – 3,995 8. Andrey Rublev – 3,935 9. Hubert Hurkacz, Poland – 3,675 10. Grigor Dimitrov, Bulgaria – 3,640 11. Alex de Minaur, Australia – 3,510 12. Holger Rune, Denmark – 3,395 13. Ugo Humbert, France – 2,535 14. Ben Shelton, United States – 2,490 15. Taylor Fritz, United States – 2,450 16. Tommy Paul, United States – 2,350 17. Karen Khachanov – 2,115 18. Alexander Bublik, Kazakhstan – 1,992 19. Sebastian Baez, Argentina – 1,955 20. Adrian Mannarino, France – 1,875