Keothavong still flies the flag in New York

The British No1 has exceeded all expectations by reaching the third round of a Grand Slam for the first time thanks to a 6-2, 3-6, 6-4 win over 25th seed Francesca Schiavone, of Italy, and is now guaranteed a show court showdown against the Olympic champion.

Dementieva has won nearly £6million in prize money and lives in Monte Carlo while Hackney-based Keothavong arrived in New York having amassed £250,000 in her career. Due to her US Open heroics she has already increased that figure by another £26,000.

Carl Maes, the head of women's tennis at the Lawn Tennis Association, expects more shocks from Keothavong. After watching her impressive win over Schiavone, he said: "Now, it's down to Dementieva to worry about British tennis.

"We all know Dementieva has a lot of power and it will be a step up for Anne in terms of dealing with that. However, Dementieva has been hit by problems with her serve in the past and it's going to be a great experience for Anne."

Since putting up a strong fight while losing her Wimbledon second-round match to eventual champion Venus Williams, Keothavong has consolidated her place in the top 100 and her success here will significantly improve her ranking of 87.

Showing the kind of superstition shared by many tennis players, the 24-year-old will insist that her LTA coaches, Nigel Sears and Claire Curran, sit in exactly the same seats at a French restaurant they have found in New York and used before the previous two wins. "I will order fish of the day and they can have anything they want as long as we finish with creme brulee for dessert," she said.

Keothavong, who is playing doubles with Anastasia Pavlyuchenkova, who at 17 is the youngest player in the top 100, is a late developer compared to the host of eastern European teenagers in the game, but it has meant she has arrived at this level with hard-earned experience of the tennis circuit.

She said: "I always felt I could do it. It was just a matter of time and it just took me a little longer than others. I really believed I had a chance to win against Schiavone and I knew if I could hang in there I would be in with a good shot.

"Schiavone is ranked a lot higher than me, she was a seeded player, and I wanted to go out there and just give it my best.

"I definitely came away from that match against Venus with a lot more confidence, and just being out there on the big stage against someone like her and not feeling too fazed was quite significant for me.

"Like I said before, it had been a goal of mine for so long to break into the top 100, and now I am working on the next goal.

"Dementieva is the Olympic gold medallist. I have never played against before but I've practised with her in the past and it will definitely be another tough match for me. But I've got nothing to lose. I feel confident, I feel fit, so who knows?"

That women's tennis in Britain has lived in the shadows for a decade is highlighted by the fact that Keothavong is the first player since 1991 to match the effort of Jo Durie and Sara Gomer in reaching the US Open third round.

"It's a nice feeling just to get women's tennis out there," she said. There are women who are doing things in British tennis, and it's nice to know that it's not just not Andy Murray out there."

Dementieva, a former beaten finalist at the French and US Opens, is supremely confident after her Beijing triumph and easily accounted for Pauline Parmentier 6-2, 6-1 while Jelena Jankovic, the No2 seed, won 6-3, 6-7, 7-5 over Sweden's Safia Arvidsson.