Age just a number for Jelena Jankovic

London: Jelena Jankovic insists she can recapture the form that took her to the top of the world after the Serbian veteran ended Petra Kvitova`s reign as Wimbledon champion.

Jankovic was ranked world number one in 2008 after reaching the US Open final and the last four at the Australian and French Opens.

But the 30-year-old had been unable to maintain that form in recent years.

She had slipped outside the top 25 after losing in the first round of three of the four Grand Slams before this year`s Wimbledon.

But, despite disliking grass courts, Jankovic was able to eliminate two-time champion Kvitova on Centre Court with a 3-6, 7-5, 6-4 third round victory that had her dreaming of a return to the upper echelons.

"I always think I can do it. I`m not old. I`m still young at heart," Jankovic said.

"I look pretty good, so why not? I mean, give me a break, guys. What`s old?

"I`m very determined. I always believe in myself, no matter what.

"Like I 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. If I`m able to work hard and believe in myself, hopefully my time will come again."

Jankovic has never reached the Wimbledon quarter-finals, losing four times in the last 16.

Only 2012 runner-up Agnieszka Radwanska stands between Jankovic and the last eight, but for now the bubbly Serb is just determined to relish every moment of her return to the spotlight.

"I cannot stop smiling. I`m really, really happy," said Jankovic, who had gone out in the Wimbledon first round three times in her last four visits.

"It`s a really big win for me, especially playing on Centre Court against a two-time Wimbledon champion.

"Grass is not my favourite surface. And Petra plays so well on it.

"But here I am in the second week of Wimbledon. I just beat a defending champion. I mean, it`s unbelievable. I hope to keep going."