Roger Federer and his wife made a surprise visit to Wimbledon on Day 8 of proceedings, scheduled for a Royal Box attendance on a blockbuster day of matches. On Center Court, the duo could catch the likes of Novak Djokovic, Emma Navarro and others take part in their fourth-round matches.Monday at SW19 on Center Court included three matches: Novak Djokovic vs Alex de Minaur, Emma Navarro vs Mirra Andreeva and World No. 1 Jannik Sinner vs Grigor Dimitrov. Meanwhile, Federer's compatriot Belinda Bencic was also in action on the day, scheduled to take on Ekaterina Alexandrova in Court No. 1.Minutes ahead of play opening on Center Court, Federer and his wife were spotted at the grounds in London, delighting fans in attendance at Wimbledon as well as on social media. The eight-time champion turned up the style in a dark blue suit and sunglasses, while his wife Mirka oozed class in an elegant white dress keeping in tone with the dress code at Wimbledon.Wimbledon has been rife with celebrities in attendance at the Royal Box this year, with Andy Roddick and wife Brooklyn Decker, Gareth Southgate, Olivia Rodrigo, John Cena, Maria Sharapova, David Beckham and others visiting in the first week of the tournament.Novak Djokovic booked his spot in the quaterfinals with Roger Federer watching from the stands, taking down Alex de Minaur in four sets. He will next take on Flavio Cobolli at SW19 after the Italian beat former Grand Slam champion Marin Cilic in the fourth round.Roger Federer was once denied entry to Wimbledon after his retirementWith eight titles to his name, one would imagine Roger Federer was one of the most unforgettable faces at Wimbledon. However, the Swiss was denied entry to the stadium in 2022 during a casual visit, an experience he found rather amusing.Speaking on The Daily Show, Federer recalled the bizarre encounter, joking about how he had forgotten his membership card and couldn't convince the security guard in front that he was actually a member of the AELTC."When you win Wimbledon, you become a member automatically. So I'm like, 'No, I don't have my membership card but I am a member and I'm just wondering where I can get in,' and she said, 'Yeah, but you have to be a member.' I was like, 'I'm just asking you again where can I get in,' and she said, 'The other side, but you have to be a member.'"The 20-time Grand Slam champion further added:"So I look at her one last time and I'm so sorry, I couldn't believe and still can't believe I said this and because I still feel bad about it. I'd look at her and say, 'I have won this tournament eight times. Please believe me, I am a member!'"Federer won Wimbledon for the final time in 2017, which also marked his 19th Grand Slam title. In 2019, he reached the final, but lost to Novak Djokovic.