However, it was a moment post-match which got the three women in the Royal Box laughing away, and it's for the most adorable reason.
"Meghan's trait of raising both her cupped hands towards her face as she talks to Kate is a cute, quasi-infantile ritual that implies a desire to show you're chatting to a best friend and sharing your message behind a partial cut-off".
Kate's mom Carole Middleton, younger sister Pippa, brother James and his girlfriend Alizee Thevenet were in attendance to witness the competitive match.
But, despite their strong bond, the 37-year-old sportswoman won't be dishing out any parenting advice to the happy couple any time soon - even though she has 19-month-old daughter Alexis Olympia with husband Alexis Ohanian.
Pippa Middleton joined her sister and brother-in-law at the prestigious tennis tournament.
Serena and Meghan have been friends for a long time, with Serena attending Meghan and Harry's wedding previous year.
Kate is an avid tennis fan and a fixture at Wimbledon.
Kate, who wore a light blue dress by Emilia Wickstead, and William watched the match from the Royal Box with Wimbledon chairman Philip Brook and his wife, as well as many other royals.
Just days before their joint appearance at the final, Meghan cheered on Serena as she faced Kaja Juvan.
The Duke and Duchess of Cambridge met with senior figures from the All England Lawn Tennis Club this afternoon before watching Federer play.
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