A total of 53 swimmers, 29 men and 24 women, representing 11 countries, competed in the sixth leg of the World Cup series in Chun'an.

Xin, who finished in fourth place at the Rio 2016 Olympic Games, showed her speed late on to coast past her rivals and touch home first in a time of 2 hours 5min 55sec.

It was the first time in history that a Chinese swimmer has won a FINA World Cup race.

Cecilia Biagioli of Argentina snatched the silver medal in 2 hours 6min 37sec with Italian Arianna Bridi, the winner of the last World Cup stage in Canada, coming third in 2 hours 6min 37sec.

Xin, who won China's first gold medal at the Asian Beach Games two weeks ago in Vietnam, said she tried to save her energy during most of the race.

"I am very happy to be the first Chinese swimmer to grab a crown in the World Cup and on top a stage held in my country," said Xin.

"I feel proud of myself and our Chinese swimmers as a whole.

"From my limited experience, the pace setters are not the final champions, so I tried to hide most of the race.

"Sometimes I was almost the last one of the group to save my energy. 

"The last one lap was very important for me, I tried my best to get away from my rivals."

In the men's race, Italy's Simone Ruffini stormed to the finish wall to claim the gold medal in a time of 1hour 56min and 1.3sec.

"I am very happy and satisfied with the victory," said Ruffini.

"It is my first time to race at the World Cup in China, and I won.

"Everything was perfect, I only started to swim faster and harder from the last lap.

"I went out of the group and went to the front. 

"It was an easy race, I think."

Germany’s Andreas Waschburger, winner of the last World Cup race and leader going into the closing stages, came in second in 1hour 56min 2.9sec.

Allan Do Carmo of Brazil completed the top three in a time of 1hour 56min and 5sec.

The next and final leg of the 2016 circuit of the FINA 10km Marathon Swimming World Cup will be held in Hong Kong on October 15.