Roger Federer and family paid a special visit to Kensington Palace in London this week during their stay for the ATP finals.

The tennis star, along with his wife Mirka and their four children, were spotted arriving at the Royal Residence with two small presents, presumably for Prince William and Kate's children, Prince George and Princess Charlotte.

The Federers have been close friends with the Cambridges since meeting at Wimbledon, and spent almost two hours together during their playdate.

The families' friendship goes way back, with Roger and Mirka attending Pippa Middleton and James Matthews' wedding in April.

Kate's younger sister Pippa even conducted an exclusive interview with the tennis star for Vanity Fair in 2013, where they discussed his breakfast choices and the Wimbledon ball after party.

She has also been spotted watching Roger play at Wimbledon from the Royal Box and at the ATP World Tour in London in 2014.

This is not the first time that Prince George and Princess Charlotte have enjoyed playdates with other celebrity children.

In 2016, they had a fun evening with Ben Affleck's son Samuel while the Hollywood actor was filming for Justice League in London.

Affleck recounted the experience during an appearance on The Graham Norton Show, revealing that he had no idea the Royals were in the indoor play park until the very end.

During their visit to Kensington Palace, Roger and family were seen leaving their hotel, which is located just around the corner from the Royal Residence.

It's no surprise that the Federers visited the Cambridges, as the two families have been close friends for years.

They are often seen spending time together, and it's clear that their bond has only grown stronger over time.

The Federer children, twin girls Mila Rose and Charlene Riva, aged 8, and twin boys Leo and Lennart, aged 3, seemed to have a great time during their playdate with Prince George and Princess Charlotte.

It's always heartwarming to see children from different backgrounds coming together and having fun, regardless of their parents' status.

It's not just the Federers who have been enjoying their time in London for the ATP finals.

The tournament has seen some incredible matches, with some of the world's best tennis players competing against each other for the title.

The atmosphere at the O2 Arena has been electric, with fans cheering on their favorite players and creating a lively atmosphere.