Their last joint event was previous year, at the 2018 ladies' final for the Wimbledon tournament.
The royals are present to support Meghan's good friend as she takes on Romania's former world No.1, Simon Halep. In 2018, the Duchesses headed to Wimbledon together, and seemingly enjoyed a lovely day out in the sun.
Meghan Markle stunned in a crisp white shirt and patterned pleated skirt for the much-anticipated women's final.More news: Boeing 737 Max chief to retire amid executive shuffle
When asked whether she hoped the royal would ignore the haters and continue to attend her matches, Serena said she "didn't know there was negative media out there".
She said recently: "I never pass on words of wisdom because I feel like for everyone - when they have a kid, especially when you just have a baby - it's so hard to just be".
"I know lots of people would like to get pictures of Meghan and I know people get cross when she gets upset because she's a public figure".More news: Marvin Brooks leaves Love Island villa
They asked: "What's the royal protocol for where Kate and Meghan are sitting?"
The Duchess of Sussex returned to Wimbledon on Saturday and wow, how incredible did she look?
She caused controversy after her royal protection officers told spectators not to take pictures of her while watching Williams on Court One because she was there "in a private capacity".
Fans cheered loudest for Meghan and Kate.The royals were on hand to watch the tennis legend chase her 24th Grand Slam title. More news: Axe falls on judge over video leak
All the children were in tow, Kate with George, Charlotte and Louis, and Meghan cradling Archie.
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