Prince William's on-off girlfriend Kate Middleton is to take part in a Dover to Calais Chinese dragon boat race.
Prince William and Kate Middleton split up earlier this year
She will be part of the all-female crew of the Sisterhood, which will race against the Brotherhood, crewed by men.
The male team have warned their female rivals to expect a tough challenge in the race later this month.
The two teams will paddle across the Channel - one of the world's busiest shipping lanes - on 25 August in aid of children's charities.
"We will give Kate's crew a sound beating," said Brotherhood spokesman David Strang.
The Beauty v Brawn race is in aid of the Babes in Arms charity, which sponsors research into abnormalities in newborn babies, and the children's hospice charity Chase.
Miss Middleton, 25, was persuaded to join the women's team by Sisterhood member Alicia Fox-Pitt, a school friend from Marlborough College.
If they complete the 20-mile trip, the women will be the first all-female team to cross the Channel in a dragon boat.
Mr Strang said Miss Middleton's involvement had been "fantastic" for raising the race's profile and drawing attention to the charities.
But he said she deserved her place in the team.
"I don't think she would be in the boat unless she had earned her place.
"The girls are very competitive and sports minded. They're not going to have a token celebrity in their team."
The Brotherhood said on Friday its captains would be Dicky Pullan, who rowed across the Atlantic in 2003, and boxer Matt Pratt, who has sparred with Nigel Benn.
Both crews are attempting to break the record for a dragon boat crossing, which currently stands at seven hours 45 minutes, the Brotherhood said.
Prince William and Miss Middleton split up earlier this year after a four-year relationship but are reported to have attended several events together during the summer.
She was seen in the Royal Box at the Concert for Diana at Wembley on 1 July.