Speaking in a video that was played at the Football Association's 150th birthday celebrations on Saturday night William revealed "when Villa thrash Man U at Villa Park, my son will be there."
"I've always loved football since I was little boy," said William, who has long supported the Birmingham-based team. "I've never got any better at it but I keep saying to myself that if you keep trying, eventually something will happen."
"No it wasn't [easy]" said the Duke of Cambridge. "There was one person I needed to get permission from and that was my grandmother.
"She was extremely supportive but it was a little bit of a sweating moment for me having to ask her."
"The possibility that her lawn might turn into a massive quagmire was a little bit awkward," he said. "But thankfully the weather held off."
New dad William stepped out to support the FA at a gala dinner on Saturday.
The Prince joined the likes of England manager Roy Hodgson, Liverpool striker Michael Owen and former England star Gareth Southgate at the Grand Connaught Rooms in London.
The Duchess of Cambridge's husband gave a speech during the evening which praised the work of football's anti-racism charity Kick it Out, but claimed that there was "sadly more work to do" regarding racism within the game.