Jelena Jankovic is vowing to laugh her way back to the top of the women's rankings by winning her first Grand Slam in New York.

The bubbly World No2 has seen fellow Serb Ana Ivanovic, the current No1, lose early in the US Open and now a host of players are trying to snatch top spot.

For Jankovic, winning at Flushing Meadows would silence the doubters who point out that she reached the top on 11 August without winning a Slam or beating a top five player this year. Jankovic is just happy to still be in the tournament after overcoming injury worries and now takes on 29th seed Sybille Bammer, of Austria, in the quarter-finals.

Jankovic said: "Regaining No1 is a goal, but I want to win a Grand Slam. I have been injured and had a tough time this year, and finally I'm feeling good at the moment.

"I am the kind of girl who likes to have fun, who likes to enjoy her time and as soon as I get off the court, I become another person.

"I am quite competitive, and a fighter on the court, but as soon as I step off the court, it's like two different girls."

World No5 Elena Dementieva, who won Olympic gold in Beijing, takes on 15th seed Patty Schnyder in the quarter-finals after easily beating Li Na 6-4, 6-1.

Former Wimbledon runner-up Marion Bartoli said it was a "miracle" she could battle on for more than three hours after she suffered from low blood pressure and a stomach virus during her 7-6, 0-6, 6-4 loss to Sybille Bammer.