Simona Halep is back up to second but missed a chance to reclaim the number one ranking. (Photo: AFP/KARIM SAHIB) |
French Open champion Halep, who last held the top spot in January, would have returned to the summit had she reached the final in Florida following Osaka's early exit.
Halep reduced Osaka's lead to 239 points and moved above Petra Kvitova after the Czech fell to eventual champion Ashleigh Barty in the last eight.
Estonia's Anett Kontaveit climbed to a best of 14th as she jumped five places following her run to the semi-finals.
WTA rankings on Apr 1:
1. Naomi Osaka (JPN) 6,021 pts
2. Simona Halep (ROM) 5,782 (+1)
3. Petra Kvitova (CZE) 5,645 (-1)
4. Karolina Pliskova (CZE) 5,580 (+3)
5. Angelique Kerber (GER) 5,165 (-1)
6. Kiki Bertens (NED) 5,050 (+2)
7. Elina Svitolina (UKR) 5,020 (-2)
8. Sloane Stephens (USA) 4,287 (-2)
9. Ashleigh Barty (AUS) 4,275 (+2)
10. Aryna Sabalenka (BLR) 3,595 (-1)
11. Serena Williams (USA) 3,461 (-1)
12. Anastasija Sevastova (LAT) 3,270
13. Caroline Wozniacki (DEN) 3,117
14. Anett Kontaveit (EST) 2,845 (+5)
15. Julia Goerges (GER) 2,835
16. Wang Qiang (CHN) 2,812 (+2)
17. Elise Mertens (BEL) 2,800 (-3)
18. Madison Keys (USA) 2,726 (-2)
19. Garbine Muguruza (ESP) 2,525 (-2)
20. Caroline Garcia (FRA) 2,460 (+1)
What the stars mean:
★ Poor ★ ★ Promising ★★★ Good ★★★★ Very good ★★★★★ Exceptional