Meghan Markle and her new sister-in-law Kate couldn't contain their excitement in the royal box at Wimbledon, where the pair enjoyed their first outing sans husbands. Dressed to the nines, the Duchesses were giggling and chatting throughout the afternoon before both looking moved as Meghan's close friend Serena Williams lost the title and dedicated her game to "all the mums".
Fans couldn't help remember another famous set of sisters-in-law: Princess Diana and Sarah Ferguson. The equally stylish duo used to gallivant around together at official royal events, but also courtside at Wimbledon and in the stands at polo matches. The friendship between Prince Charles' late wife and Prince Andrew's ex was a hot topic in the '80s and '90s and, much like Meghan and Kate, royal watchers were keen to know just how authentic their friendship was.
While they'll never know for sure, the Duchess of Sussex and the Duchess of Cambridge were giving off major 'Diana and Fergie' vibes on their big day out. Click through to see the photos…
Wimbledon is an event not to be missed, and you better believe Diana and Sarah were there together in 1989! The two chatted in the stands while watching the matches.
And just like Sarah and Diana, the Duchesses of Cambridge and Sussex made their very own courtside debut in 2018. The gorgeous royals were seen chatting and applauding for the players.
While the 36-year-old Duchesses didn't share a kiss on the cheek, royal fans have this vintage photo of a sweet moment between Sarah and Diana to look back on.
The royal friends also attended the tennis championship in 1988, where Diana wore a relaxed cream suit while the Duchess of York opted for a polka-dot blouse.
Despite Serena Williams' loss, Kate and Meghan had the best of times. Of particular note were their beautiful outfits, with the Duchess of Sussex looking cool in a nautical-themed Ralph Lauren ensemble while Kate stunned in polka dot Jenny Packham.
The Princess of Wales and the Duchess of York were dressed to impress on the balcony of Buckingham Palace during the Trooping the Colour ceremony in June 1991. The Princess donned a Catherine Walker suit and Philip Somerville hat.
Another first for Meghan was that very event in 2018, when the two Duchesses - each clad in a beautiful pastel ensemble - shared a friendly moment on the Buckingham Palace balcony during the flypast.
The Duchess of York and the Princess of Wales had a ball in the stands at the Guard's Polo Club in Windsor in June 1983. Fergie wore a blue floral-printed dress with oversized sunnies while Diana stayed snug with a sheep-printed sweater from the London shop Warm And Wonderful.
Royal Ascot in 1991 was all about bigs hats and bigger friendships! Sarah and Diana were thick as thieves at the annual event, even down to their coordinated outfits.
Sarah and Diana rocked wide-brimmed hats while at the Epsom Downs together.
Easter is for pastels! In 1991, the royal women stepped out for an Easter service at Windsor Castle, perfectly paired in pale pink ensembles. A young Prince William stood behind the duo.
Though their sense of style was different, royal watchers were always eager to see what the dynamic duo would wear when stepping out together.
Similarly, fans of Duchesses Meghan and Kate are always patiently waiting to see how their looks can be compared. While at the first-ever Royal Foundation Forum in February 2018, the royal women stuck with blue hues but styled their looks very differently.
Princess Diana and Sarah wore equally striking outfits for Christmas at Sandringham in December 1988.
Meghan and Kate had a friendly chat as they walked at Sandringham for their very first Christmas together in 2017 after the former actress and Prince Harry announced their engagement.