Li Na's Australian Open triumph last month was followed by a stunning tumble when she lost to a qualifier in the third round of the Qatar Open. Photo by: Fadi Al-Assaad/Reuters

Doha – Top-seeded Li Na's Australian Open triumph last month was followed by a stunning tumble when she lost to a qualifier in the third round of the Qatar Open on Thursday.

The celebrated Chinese player was beaten 7-6 (7-2), 2-6, 6-4 by Petra Cetkowska, a Czech ranked outside the top 100, in a topsy-turvy contest in Li's first tournament since her Grand Slam triumph in Melbourne.

She seemed to have turned the match around when she came from behind to lead 3-1 in the final set, but then appeared to run out of steam in a two-hour 46-minute contest in which her ratio of errors increasingly soared.

Her consolations are that she will still be world number two for the first time - the highest ever by an Asian player - at the end of the week, and that she mostly stuck to an ambitiously aggressive game plan despite a disruptive wind.

“I don't think my performance was so bad,” Li said. “Though if I had continued more coming to the net it would have been better. A defeat is not always so bad either. At least I fought and I got information from what happened. I will put that information straight into my training.”

Li paid tribute to Cetkowska, whose performance suggested she is recovering well from injuries which caused her to plunge from the world's top 30.

Nevertheless, Li had so many chances to take hold of the contest, having game points to lead 3-0, 4-1, and 5-3 in the final set, and yet was unable to convert any of them.

“I was well down in the third set so I am very happy to come back,” said Cetkowska. “This is a tennis match - so such things can always happen. It will give me a lot of confidence.”

Li appeared to have benefited from a highly charged incident in the second set when she might have gone a set and a break of serve down.

After swinging a ferocious backhand drive towards the baseline, she heard the shot called out, with a lunging Cetkowska barely able to touch it.

Had that decision stood, Li would have been down by a set, 1-2

and 15-40. However her appeal to the video review system succeeded, the ball appearing to have touched the back edge of the line, and the score was changed to 30-all instead.

Cetkowska protested that the “out” call was audible before she had made her stroke, and that the point should therefore have been replayed, but this was rejected.

The Czech's standard dropped markedly after that, with Li taking seven successive games to lead 2-0 in the final set.

However, the 31-year-old then appeared to tire, and Cetkowska took advantage to advance and set up a quarter-final with Angelique Kerber, the sixth-seeded German.

Later, Petra Kvitova, the third-seeded former Wimbledon champion, also struggled, trailing 3-5 in the first set and squandering a three-game recovery in the second set, before surviving 7-6 (7-2), 5-7, 6-2 against Lucie Safarova, her fellow Czech.

Kvitova, perhaps motivated by the thought that she has champion's ranking points to defend in a Serena Williams-led field at Dubai next week, now plays Jelena Jankovic, the former world number one from Serbia.

Later there was some consolation for Chinese supporters when Peng Shuai became certain of becoming the first Chinese player ever to top a world ranking.

After she and Hsieh Su-Wieh, her Taiwanese partner, won their first-round doubles by 6-2, 6-4 against the Ukrainian-Russian combo of Irina Buryachok and Vitalia Diatchenko, they had earned enough points to climb above the current world number ones, Roberta Vinci and Sara Errani of Italy.

Peng, though, claimed to have been unaware of the accolade. “No, I didn't know,” she said. “The coaches came and said congratulations. And I said 'are you sure?'“ – Sapa-AFP