Prince William says his cheering for his football team left his three children stunned.
The lifelong Aston Villa fan, 38, says he can get quite carried away when he watches a live game.
Held to raise awareness for his charity , he spoke to the crowd ahead of the game.
Here he said he scared his children last Sunday during Aston Villa's draw with West Ham.
Prince William's football passion
He said: "The nerves were the worst I've ever known them. My children looked at me in horror as I was jumping off the sofa, screaming my head off."
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"It's very good news that as president of the FA I can hide away until these moments, and I'm not visibly seen because it was one of the most stressful moments of my life, as I imagine every Villa fan felt on that day."
And while the FA cup final didn't feature his team, but rather Arsenal vs Chelsea - he accurately predicted the outcome.
Prior to the game he predicted that Arsenal would win 2-1 - and they did just that.
Why does Prince William support Aston Villa?
Although his children may have been a little put off by their dad's football enthusiasm - they are by no means strangers to the game.
Last year William took his eldest two, George and Charlotte, to their first ever Aston Villa game.
Prince George won legions of Aston fans after he raucously cheered as they scored a goal.
Back in 2015 William explained to BBC host Gary Lineker why he chose the team as his own.
He said: "A long time ago at school I got into football big time. I was looking around for clubs. All my friends at school were either Man United fans or Chelsea fans and I didn’t want to follow the run of the mill teams.
"I wanted to have a team that was more mid-table that could give me more emotional rollercoaster moments.
"Aston Villa’s always had a great history. I have got friends of mine who support Aston Villa and one of the first FA Cup games I went to was Bolton v Aston Villa back in 2000. Sadly, Villa went on to lose to Chelsea.
"It was fantastic, I sat with all the fans with my red beanie on, and I was sat with all the Brummie fans and had a great time."
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