Novak Djokovic moves closer to Steffi Graf's No. 1 record, Ashleigh Barty continues to lead WTA rankings, Opelka & Giorgi make big gains

Novak Djokovic and Ashleigh Barty continue to lead the men's and women's world rankings respectively. The ATP and WTA tours released their latest rankings on Monday, with Djokovic and Barty extending their reign atop the rankings for yet another week.

Djokovic began his record-extending 334th week as World No. 1 on Monday. That means he is now 44 weeks away from breaking Steffi Graf's mark (among both men and women) of 377.

Having won the first three Majors of 2021, Novak Djokovic is also on course to become the first male player since Rod Laver to complete the Calendar Grand Slam. Djokovic is ranked comfortably ahead of his rivals in the lead-up to the US Open, despite sitting out last week's Toronto Masters and this week's Cincinnati Masters.

Toronto champion Daniil Medvedev remains at No. 2 in the ATP rankings, and is now 1,493 points behind Djokovic. There is no change in this week's top 10 as Medvedev is followed by Stefanos Tsitsipas at No. 3, Rafael Nadal at No. 4 and Olympic gold medalist Alexander Zverev at No. 5.

Roger Federer, who announced on Sunday that he would require to undergo a third surgery on his knee and would be out for 'many months', remains at No. 9. Federer, Nadal and Djokovic are the only players among the top 10 who are not competing in Cincinnati this week.

Outside the top 10, Capser Ruud, already the highest-ranked Norwegian in the history of the sport, climbed one spot to No. 11. Meanwhile Toronto finalist Reilly Opelka moved up nine spots to a new career-best No. 23; Opelka is now the top-ranked American on the ATP tour.

His countryman John Isner, who lost in the semifinals at Toronto, moved up four spots to No. 26. And Australia's James Duckworth, who reached the Toronto Round of 16, moved up 16 spots to a new career-best of No. 69.

Ashleigh Barty begins 89th week as World No. 1

Ashleigh Barty continues to lead the WTA rankings

On the WTA tour, Ashleigh Barty began her 89th week at the summit. Her reign atop the world rankings is already the ninth longest in women's tennis history.

The Aussie is followed by, in order, Naomi Osaka, Aryna Sabalenka, Montreal runner-up Karolina Pliskova and Sofia Kenin. Pliskova moved up two spots with her strong run in the Canadian city, helping her return to the top 5.

Elina Svitolina (-1), Bianca Andreescu (+1), Iga Switaek (-1), Garbine Muguruza, and Barbora Krejcikova round out the top 10. Nine of the top 10 (aside from Kenin) will be battling it out for the Western & Southern Open title this week in Cincinnati.

Montreal champion Camila Giorgi climbed 37 spots to No. 34, moving within touching distance of her career-best ranking of No. 26.

Former World No. 1 Victoria Azarenka, a quarterfinalist in Montreal, moved up two spots to No. 13. Meanwhile Ons Jabeur climbed two spots to No. 20, marking her top 20 debut.

23-time Grand Slam winner Serena Williams, absent from Cincinnati this week, dropped one spot to No. 21. That is Williams' lowest ranking since August 2018, when she was working her way back from a maternity break.

In-form Americans Jessica Pegula and Danielle Collins moved up four spots and one spot respectively to No. 26 and No. 27.