Families across the country will be gathering around their TVs, hoping for an England victory as they face Spain for the Euro 2024 title.
King Charles is expected to be cheering for the Three Lions in their highly-anticipated match in Berlin.
He has already extended the Royal Family's "best wishes" and "warmest congratulations" to manager Gareth Southgate and the team for reaching the final.
However, he also offered some serious advice ahead of the big game, stressing the importance of avoiding any last-minute drama for the sake of the nation.
In a message earlier this week, he humorously referenced the recent tense moments for England fans, including a last-minute equalizer against Slovakia in the second round and a penalty victory over Switzerland in the quarter-finals, urging the team to keep the nation's "blood pressure" in check during the final against Spain.
He said: "My wife and I join all our family in wishing you the warmest congratulations on reaching the final of the UEFA. European Championship – and in sending our very best wishes for Sunday's match.
"If I may encourage you to secure victory before the need for any last-minute wonder-goals or another penalties drama, I am sure the stresses on the nation’s collective heart rate and blood pressure would be greatly alleviated! Good luck, England."
It came after even more drama in Wednesday night's semi-final when Aston Villa striker Ollie Watkins scored a 90th-minute winner to send them through.
The Three Lions fell behind after seven minutes to a Xavi Simons strike but a controversial Harry Kane penalty, awarded by VAR, brought the scores level 10 minutes later.
The Prince of Wales, who is a Villa fan, also congratulated England and singled out Watkins for praise in a message on social media. He said: “What a beauty, Ollie! Congratulations England! #EURO2024 Finalists.”
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