While at the match, Meghan was seen hugging Serena's husband, Alexis Ohanian, before settling in to watch the women's final, which ultimately saw Serena lose to Bianca Andreescu.
For the occasion, Meghan wore a low-key outfit consisting of a denim shirt dress, a long grey cardigan and sunglasses by her friend, Victoria Beckham. According to the Twitter account @MeghansMirror, which documents all of the duchess' looks, she is wearing a J. Crew denim shirtdress with a tie belt, which was on sale for 40 per cent off until the Meghan Effect took hold and the item sold out.
In a sweet nod to her family, Meghan accessorised with a small gold necklace with two tags, one with an 'H' for Prince Harry and the other with an 'A' for Archie.
While she was in the USA, Meghan also took the opportunity to take an imprompu public yoga class at Modo Yoga in New York's West Village and surprise her friend and makeup artist, Daniel Martin, for his birthday.
Martin, who was the one to share the now-iconic photo of avocado on toast that Meghan made him, took to Instagram to write: "Thanks to everyone for reaching out to me today and Meg, love you friend for surprising me on my special day 🥰❤️"
Flying to another country to support your friends and attend their birthday parties? We're pretty sure Friend of the Year should go to Meghan Markle.