Japan's Naomi Osaka is second with Karolina Pliskova of the Czech Republic third and Romania's Wimbledon champion Simona Halep fourth. Kiki Bertens of the Netherlands rounds out the top five.

Latest WTA rankins released Monday:

1. Ashleigh Barty (AUS) 6605 pts
2. Naomi Osaka (JAP) 6257
3. Karolina Pliskova (CZE) 6055
4. Simona Halep (ROU) 5933
5. Kiki Bertens (NED) 5130
6. Petra Kvitova (CZE) 4785
7. Elina Svitolina (UKR) 4638
8. Sloane Stephens (USA) 3802
9. Serena Williams (USA) 3411
10. Aryna Sabalenka (BLR) 3365
11. Anastasija Sevastova (LAT) 3136
12. Belinda Bencic (SUI) 2963
13. Angelique Kerber (GER) 2875
14. Qiang Wang (CHN) 2872
15. Johanna Konta (GBR) 2790
16. Marketa Vondrousova (CZE) 2762
17. Madison Keys (USA) 2555
18. Caroline Wozniacki (SUI) 2478
19. Anett Kontaveit (EST) 2335
20. Elise Mertens(BEL) 2305 (+1)