The Beijing games mark the first time the women's 10km swim marathon has been held as an Olympic event.
An hour into the race held in Beijing’s Shunyi rowing-canoeing park British duo Payne and Patten had opened up a five metre gap over the leaders, including Ilchenko.
|The race marked the Olympic debut of the women's swim marathon [GALLO/GETTY]
But as the two hour mark approached the two Britons began to tire and the Russian was able to pull ahead in the final 100 metres.
South African amputee du Toit finished in 16th place with a highly respectable time of 2 hours 49.9 seconds, despite the fact that she lost most of her left leg seven years ago following a motor scooter accident.
"I went out there and gave it everything, which was my goal," she said. "I had a good race but I'm glad it is over.
"In another couple of days I've got the Paralympics so I've got to get back in that water and train."