Royals Royal Rugby Rivalry! Princess Kate and Prince William Sing Welsh Anthem (in Welsh!) and Prince Harry Cheers on England Decked out in their Countries Colors William and Harry and Princess Kate attend big rugby match By Simon Perry Simon Perry Simon Perry is a writer and correspondent at PEOPLE. He has more than 25 years’ experience at PEOPLE covering the royals, human interest and celebrity. People Editorial Guidelines Published on September 26, 2015 04:00PM EDT Photo: AP There’s nothing like a bit of sibling rivalry to spice up a sports event. Prince William and Prince Harry were pitched against each other on Saturday during the biggest match of the Rugby World Cup when they backed opposing nations. The brothers, and Princess Kate, were back in the stands, where they had been for the opening ceremony Sept. 18, to watch England take on Wales at Twickenham, London. William and Kate were rooting for Wales while Harry backed England. Kate and William, both 33, could be seen at the start heartily singing the Welsh national anthem – in Welsh, no less – a clear sign of their support. William donned the Welsh jacket while Harry wore a white shirt for England. Harry, 31, is honorary president of the World Cup and vice-patron of the body that runs English rugby. William, meanwhile, is the vice patron of the opposite organization in neighboring nation, the Welsh Rugby Union. The couple singing the anthem will go down well in Wales. Even before they wed, Kate pleased the locals by taking part in singing the Welsh anthem when she and William opened a new lifeboat station in North Wales. William has said that he is Welsh at heart. “I asked him who he was supporting and he said he was a Welshman at heart, but Harry was England. I told him that I hoped he would be crying into this beer at the weekend while at Harry would be celebrating, and he said that was what normally happened,” Andy Walton, a former sergeant major in the Royal Engineers who met William as he helped volunteers and veterans build homes for ex-servicemen this week, told reporters. And he left the Welsh team in no doubt as to his allegiances when he met them Monday. “Unfortunately I will be watching you with my brother, so I will need a Wales win more than ever.” The double-effort of William and Kate may have paid off as Wales beat England 28-25. Kate was spotted grinning when Wales came up from behind with four minutes left. William and Kate lived a quiet life in Anglesey, Wales, for the first three years of married life, when William served as an RAF search and rescue helicopter pilot. Want to keep up with the latest royals coverage? Click here to subscribe to the Royals Newsletter.