Serena Williams is the queen of tennis, and sports royalty.

But Saturday she’ll be playing before real royalty, with longtime pal Meghan Markle hopping the pond to watch the US Open final.

It’s a last-minute trip for the Duchess of Sussex, but that’s what happens when your pal is going for history. Williams will be looking to match Margaret Court’s all-time record of 24 Grand Slam singles titles, having been stuck on 23 for the past two years since childbirth.

Williams faces 15th-ranked Canadian teenager Bianca Andreescu on Saturday in Arthur Ashe Stadium.

Their friendship stretches back almost a decade. Williams first met Markle back at the 2010 Super Bowl in Miami, and they quickly became pals.

Williams and husband, Alexis Ohanian – the co-founder of Reddit – both attended the royal wedding last summer, and joined Markle in watching husband, Prince Harry, play in a polo match in Ascot, England. Now Markle will be watching her compete in a slightly higher-level athletic endeavor.

This is Markle’s first solo trip without 4-month-old son Archie, and her first stateside since a February baby shower in New York. Fittingly, it was Williams – a new mother herself – who helped throw the shower for Markle.

Williams has made four Grand Slam finals since giving birth to daughter Olympia two years ago, and lost the first three to remain a single crown behind Court. She stormed through Thursday’s semifinal, and just seven hours later, the Duchess of Sussex caught a flight – commercial, no less – to cheer her on in the final.