Tennis - Li sent packing from Doha

Top seed Li Na was ousted from the Qatar Open after being shocked 7-6(2) 2-6 6-4 by Petra Cetkovska in the third round in Doha.

Prior to facing the Czech qualifier, Li had not lost this year following her successes at the WTA tournament in Shenzhen and at the Australian Open.

In a largely evenly-matched encounter, new world number two Li laid the blame for her loss on her inability to win the big points - and the poor conditions which players have had to cope with.

"She played well. I don't think I was playing so bad," Li said. "Maybe, sometimes the wrong choice made me lose a lot of important points.

"It was cold. It's windy. The court is a little slower. When I think I can hit a winner the opponent always gets the ball back, so I always have to be ready for the next shot."

Cetkovska, who has now beaten a top 10 player eight times, said: "It's an amazing victory. It's a little bit difficult to describe exactly what I feel at the moment.

"Even though I was 3-1 down in the third set I could manage to make it and get through."

The world number 139 next meets Angelique Kerber, who beat Klara Zakopalova 6-2 6-3.

Meanwhile, second seed Agnieszka Radwanska walked through to the quarter-finals after her third-round opponent Mirjana Lucic-Baroni retired with a lower back injury with the scores 6-4 0-1 in the Pole's favour.

Radwanska will now play Yanina Wickmayer for a place in the semi-finals.

Petra Kvitova, seeded third, was pushed all the way by fellow Czech Lucie Safarova before the former Wimbledon champion closed out a 7-6(2) 5-7 6-2 victory.

Kvitova had 15 aces on her way to setting up a last-eight meeting with Jelena Jankovic.

"I served well, yes," said Kvitova, the 2011 Wimbledon champion. "I had one window when I did some double-faults, unfortunately. But with the aces I'm really glad."

Fifth seed Jankovic sealed her progress with a comfortable 6-1 6-2 win over Alisa Kleybanova

In Friday's other quarter-final, fourth-seeded Sara Errani faces seventh-seeded Simona Halep.

Qatar Open results

Third round

7-Simona Halep (Romania) beat Annika Beck (Germany) 6-4 6-1

Yanina Wickmayer (Belgium) beat Jana Cepelova (Slovakia) 1-6 6-2 6-0

2-Agnieszka Radwanska (Poland) beat Mirjana Lucic-Baroni (Croatia) 6-4 0-1 (Lucic-Baroni retired)

3-Petra Kvitova (Czech Republic) beat Lucie Safarova (Czech Republic) 7-6(2) 5-7 6-2

6-Angelique Kerber (Germany) beat Klara Zakopalova (Czech Republic) 6-2 6-3

4-Sara Errani (Italy) beat Monica Niculescu (Romania) 2-6 7-5 6-1

Petra Cetkovska (Czech Republic) beat 1-Li Na (China) 7-6(2) 2-6 6-4

5-Jelena Jankovic (Serbia) beat Alisa Kleybanova (Russia) 6-1 6-2