The royal pair, whose wedding last summer prompted a mass outpouring of patriotic delight in London, decided to shun the VIP seating available to them in favor of a regular spot in the stands while watching Great Britain's Andy Murray play Nicolas Almagro of Spain.
William and Kate would have been eligible to sit in Center Court's Royal Box, which is reserved for special visitors to the All England Club. But as Murray was playing his quarterfinal on Court One, they instead opted for a normal pair of seats to the left of the players' box.
Olympic organizers made significant changes to the allocation of ticket levels in the lead up to and during the Games. However, it is believed that the seats where William and Kate sat were in the "B" category and priced at 85 pounds ($132) each. The most expensive seats were those situated a few feet from the action at court level.
As the good-natured crowd put its support behind home hopeful Murray, whose 6-4, 6-1 victory put him through to Friday's singles semifinals, the royals even joined in and raised their arms as the audience put together an impromptu "wave."
They were briefly joined by the president of the international tennis federation, the marvelously named Francesco Ricci Bitti. Other senior members of the tennis fraternity also stopped by.
[ Photos: Royals and celebrities at the Olympics ]
William and Kate have been to many sports since the start of the Olympics, including equestrian to watch the Queen's granddaughter Zara Phillips win a silver medal in the three-day team competition.
They were also spotted at water polo, the sport William played the most in college. William was seen yelling out advice to the Great Britain squad as it stumbled to a heavy defeat.
Fans at Wimbledon responded warmly to the pair on Thursday.
"They were quite close to us, and you could see they were having a wonderful time," said Emma Dalton of Epsom, just outside London. "It was actually nice that Murray was on Court One, so they could be a bit closer to everyone. Otherwise, I'm sure they would have been tucked away in the Royal Box."
[ Photos: Colorful tennis fashion invades Wimbledon ]
Murray's matches are becoming regular viewing for the royal family, with his run to the final of the Wimbledon Championships this summer being seen by William, Kate, Prince Harry, Prince Charles, and the Queen.
"It is always nice playing in front of royalty," the British world No. 4 player said. "They came a couple of times during Wimbledon as well. I probably dealt with it a bit better this time than I did the first couple of times. I think it is great for tennis when you can get people like that coming along. It helps raise the profile."
More London Olympics coverage on Yahoo! Sports:
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- Royal Families
- Prince William
- Andy Murray
- William and Kate