Naomi Osaka moved up one spot to second in the WTA rankings released Monday following her success at the Australian Open, as she won her fourth Grand Slam title. The Japanese star beat Jennifer Brady of the US in straight sets in the final to lift the trophy in Melbourne for the second time in three years. Osaka, 23, trades places with Simona Halep, the Romanian dropping down to third after losing to Serena Williams in the quarter-finals. Williams jumps up four places to seventh despite again falling short of a record-tying 24th major. The American was beaten by Osaka in the semi-finals. The 25-year-old Brady, a semi-finalist at last year's US Open, reached a career high of 13th on the back of her best Grand Slam performance to date. Ashleigh Barty remains the world number one in spite of losing in the last eight to Karolina Muchova, who gained five spots in rising to 22nd. WTA rankings as of February 22: 1. Ashleigh Barty (AUS) 9186 pts 2. Naomi Osaka (JPN) 7835 (+1) 3. Simona Halep (ROM) 7255 (-1) 4. Sofia Kenin (USA) 5760 5. Elina Svitolina (UKR) 5370 6. Karolina Pliskova (CZE) 5205 7. Serena Williams (USA) 4915 (+4) 8. Aryna Sabalenka (BLR) 4810 (-1) 9. Bianca Andreescu (CAN) 4735 10. Petra Kvitova (CZE) 4571 (-2) 11. Kiki Bertens (NED) 4505 (-1) 12. Belinda Bencic (SUI) 4010 13. Jennifer Brady (USA) 3765 (+11) 14. Victoria Azarenka (BLR) 3535 (-1) 15. Garbine Muguruza (ESP) 3320 (-1) 16. Johanna Konta (GBR) 3206 (-1) 17. Elise Mertens (BEL) 3060 (-1) 18. Iga Swiatek (POL) 3014 (-1) 19. Madison Keys (USA) 2962 (-1) 20. Marketa Vondrousova (CZE) 2952 bur-mw/