The Prince of Wales shook hands with King Frederik X of Denmark after their teams drew their Euro 2024 match 1-1.
The pair were seen smiling and chatting in the stands at the end of the game.
Shortly after kick-off, a photo of William, Frederick and Princess Josephine of Denmark was shared to the Wales’s X account with the caption: “May the best team win.”
Long-time football fan William, who turns 42 on Friday, was photographed laughing with Frederik in the crowd and the pair were filmed having an enthusiastic conversation.
William was wearing a suit and striped tie and Frederik an open-collar white shirt and blazer at the Frankfurt Arena in Germany.
The Prince of Wales was also snapped shaking hands with Uefa treasurer David Gill.
A 1-1 draw means England are still in the driving seat to qualify from the group.
Harry Kane scored the opener, putting England 1-0 ahead after 18 minutes, before Morten Hjulmand arrowed home a low strike from 30 yards to level for the Danes.
But former England defender Rio Ferdinand bemoaned the tactics adopted by manager Gareth Southgate.
Asked about the performance, he told BBC One: “Lacklustre, lacked any sort of direction in my eyes, tactically well below par – we were overshadowed tactically, I thought, by the Denmark team.”
William is a passionate Aston Villa fan and he presented shirts to the England men’s squad before the team left for Germany, making a surprise visit to St George’s Park, England’s national football centre in Burton upon Trent.
He attended the game alone, as the Princess of Wales is away from public duties while she continues her treatment for cancer.
On Wednesday, William joined Kate’s parents at Royal Ascot along with a host of royals including the Queen.
Kate, 42, revealed in a statement last Friday she is making “good progress” in her treatment but candidly said she has “good days and bad days” and, although she has been working from home, stressed “I am not out of the woods yet”.
In March, she announced she is undergoing treatment for cancer in an emotional video message.
In the message revealing the diagnosis, she said: “This of course came as a huge shock, and William and I have been doing everything we can to process and manage this privately for the sake of our young family. As you can imagine, this has taken time.
“It has taken me time to recover from major surgery in order to start my treatment.
“But, most importantly, it has taken us time to explain everything to George, Charlotte and Louis in a way that is appropriate for them, and to reassure them that I am going to be OK.”
Since revealing the diagnosis, the Prince and Princess of Wales are said to be “enormously touched” and “extremely moved” by the public’s warmth and support.
