Prince Harry and the Duke of Cambridge will take part in a charity polo tournament in aid of disadvantaged African children.
The royal brothers will play in the Sentebale Polo Cup - an event in aid of Harry's Sentebale charity.
The prince, 26, will play for a Sentebale team against William, 28, who will turn out for a Tusk Trust team, a conservation charity of which he is royal patron.
A third group of players are being sponsored by Bin Drai Enterprises - a Dubai-based family office.
Organisers had originally planned to stage the Cup in Dubai but it was postponed because of the unrest in the Middle East, and rescheduled for Coworth Park in Berkshire.
The three teams will play each other in a round-robin tournament with Harry's group of players taking on Tusk Trust in the final match of the day.
When the event was postponed earlier this year, a St James's Palace spokesman said the 26-year-old royal felt it was insensitive to hold a sporting event when there were "matters of greater priority to focus on in the region".
This is the second Sentebale Cup, after Harry and Prince Seeiso of Lesotho, co-founders of Sentebale, launched the event at the Apes Hill Polo Club in Barbados in January 2010.
Harry and Seeiso founded the Cup to focus attention on, and raise funds for, Sentebale - the charity they created to help disadvantaged children in the African kingdom of Lesotho.
The Sentebale charity works by supporting organisations and bodies which aim to help Aids orphans or poverty-stricken youngsters.