JELENA Jankovic has won a Wimbledon title before - the mixed doubles with Jamie Murray back in 2007 - but she has yet to triumph in a major singles event, the closest she has come so far being in 2008 when she was runner-up to Serena Williams at the US Open.

She will at least, however, fancy her chances of getting at least that far this time after a stunning three-set victory over Petra Kvitova, the defending champion.

The lower half of the draw had already been opened up the first-round defeat of Simona Halep, the No 3 seed. The elimination of Kvitova, who also won the event in 2011 and was seeded second, has blown it wide apart.

There was nothing in the first set of the match on Centre Court to suggest that the Czech woman would be in trouble, as she took it 6-3 in less than half an hour. But Jankovic hit back to win the second 7-5, and in the decider put Kvitova under increasing pressure before eventually taking it 6-4.

"I'm not really sure what happened out there," Kvitova admitted. "Suddenly I felt like she''s coming back, playing a little bit aggressive. Suddenly from my side, I didn't have answer for it."

Jankovic's serve, a serious weakness in the past, was the key to her victory. She believes she still has a long way to go before getting back to the form that took her to No 1, but she is confident that she is heading in the right direction. "I'm very determined," she said.

"I want to get to where I think I belong. I've done it in the past. I've been many years in the top 10, I've been No. 1 in the world, I've played against all these players. If I'm able to work hard and believe in myself, hopefully my time will come again.

"I don't think a lot of people believed I could win, and I did. So I think that's why I'm here. So unbelievable."

Jankovic's opponent in Monday's fourth round is Agnieszka Radwanska. The No 13 seed from Poland beat Australia's Casey Dellacqua 6-1, 6-4.

Amidst the barrage of statistics with which Wimbledon's electronic information boards bombard the visitor, one stood out as Day 6 began. After the first five days of the Championships, two players had preserved a 100 per cent record on their own serve: Roger Federer in the men's singles, and Timea Bacsinszky in the women's.

It would have been a surprise to many to see Bacsinszky, a 26-year-old from Lausanne, up there alongside her compatriot, because she is one of those players who has risen through the rankings almost surreptitiously. And, although she is the No 15 seed this year, not long ago she was thinking of giving up tennis and turning to hotel management.

You would say that Bascinszky had become disillusioned with tennis, only the reality was that she had never really loved it in the first place. Forced into the sport by her father at a very early age - "I have a father who put me in a cage", is how she described it earlier this year - she had an unhappy childhood and adolescence.

She had bags of talent too, twice winning the Little Aces, the world championship for under-14s, but only recently, having gladly become estranged from her father, has she been able to make the most of it. And she is making up for lost time.

After reaching the third round at the Australian Open, Bascinszky made it to the semi-finals at Roland Garros, beating Petra Kvitova before losing to Serena Williams. Now, thanks to a 6-3, 6-2 victory over former finalist Sabine Lisicki, she is through to the last 16 here, and on Monday will be a strong favourite to reach the quarter-finals when she takes on the unseeded Romanian Monica Niculescu, who beat Kristyna Pliskova 6-3, 7-5 and has yet to play a seed.

Fifth seed Caroline Wozniacki also progressed in straight sets, beating Camila Giorgi, the No 31, 6-2, 6-2. Wozniacki now meets Garbine Muguruza of Spain, the 20th seed, who beat No 10 Angelique Kerber in three sets.

Madison Keys beat Tatjana Maria 6-4, 6-4 and now meets Olga Govortsova of Belarus. Govortsova beat Magdalena Rybarikova of Slovakia 7-6, 6-3.