Chinese tennis great Li Na said US Open champion Naomi Osaka can go on and win multiple grand slam titles - if she can find the inner desire to match her physical abilities.
Osaka has conceded feeling burdened by expectations after last month's stunning victory in New York, saying she puts pressure on herself to "do more, do better".
The 20-year-old world No 6 was also in tears after her "bittersweet" US Open win, which was marred by Serena Williams' explosive row by the chair umpire.
"I believe with her abilities and strength, she can win many [grand slam titles] - that is if she really has the desire to be a champion," Li told AFP ahead of the Hong Kong Open.
Osaka, Asia's second grand slam singles champion after Li, has pulled out of the Hong Kong tournament with a back injury.
Williams, 37, brought a halt to her season after the US Open final, where her latest attempt at a record-equalling 24th major title ended in acrimony.
Naomi Osaka with Li Na in July
But Li, the former French Open and Australian Open winner who retired in 2014, cautioned that it was unwise to judge Williams, who is back on the circuit after becoming a mother last September.
"Looking at the players from the sidelines, we might not really understand some of their psychological goings-on on the court," Li said.
"I've always thought she is a very strong player. There are very few players who can give birth and then immediately come back out," she added.
"For me, it's really hard to find a balance between family and the tennis court, but she very quickly got into the US Open final."
Li is often credited with igniting tennis interest in Asia and especially in China, but she said the sport still had a long way to go.
"Tennis in Asia is still in its adolescence. We have just passed the infancy stage, so we can still go a lot further," Li said.
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Osaka up to No 4 in rankings
Meanwhile, Osaka rose to fourth place in the latest WTA rankings released on Monday on the strength of her outstanding form in recent weeks.
Romania's Simona Halep tops the table ahead of second-placed Caroline Wozniacki of Denmark with Germany's Angelique Kerber holding onto third place.
Osaka, aged 20, who reached the semi-finals of the China Open last week, moves up from sixth to fourth place on 4,770 points and is closing in on Kerber, who has 5,400 points.
Rankings:
1. Simona Halep (ROU) 7421 pts
2. Caroline Wozniacki (DEN) 6490
3. Angelique Kerber (GER) 5400
4. Naomi Osaka (JPN) 4770 (+2)
5. Elina Svitolina (UKR) 4350
6. Karolina Pliskova (CZE) 4345 (+1)
7. Petra Kvitova (CZE) 4255 (-3)
8. Sloane Stephens (USA) 4022 (+1)
9. Julia Goerges (GER) 3785 (+1)
10. Kiki Bertens (NED) 3740 (+1)
11. Aryna Sabalenka (BLR) 3265 (+5)
12. Anastasija Sevastova (LAT) 3240 (+8)
13. Garbine Muguruza (ESP) 3170 (+2)
14. Daria Kasatkina (RUS) 3150 (-2)
15. Elise Mertens (BEL) 3115 (-1)
16. Caroline Garcia (FRA) 3045 (-8)
17. Serena Williams (USA) 2976
18. Jelena Ostapenko (LAT) 2863 (-5)
19. Madison Keys (USA) 2816 (-1)
20. Ashleigh Barty (AUS) 2605 (-1)