Meghan Markle supports Serena Williams in the US Open Finals wearing all-American denim dress

Royal's outfit was purchased from high street favourite J.Crew

The Duchess of Sussex supported her friend, tennis star Serena Williams, at the US Open Finals on Saturday as she went head to head with Bianca Andreescu.

Meghan Markle sat in prime position in the players' box at Arthur Ashe Stadium alongside American Vogue editor Anna Wintour and Williams’ husband Alexis Ohanian.

For the occasion, Markle embraced the all-American spirit wearing a denim wrap dress by US high street favourite J-Crew.

The dress, which features a fitted tie-waist and costs £132, is currently sold out online.

However, the pale grey jacket that the Duchess draped over her shoulders is still available to purchase via their website for £165.

Markle accessorised her look with a pair of aviator-style sunglasses clasped on her dress and maintained her usual relaxed approach to beauty with minimal makeup and her hair in tousled waves.

The trip marks Markle’s first journey overseas since she gave birth to her four-month-old son, Archie.

Markle wore a dress and sweater-blazer by J.Crew (Getty Images)

The royal’s last trip to America was in February for her baby shower with close friends.

Markle first met Williams at the 2010 Super Bowl in Miami.

In July, Markle also attended Williams’ match at the Wimbledon championships and was later joined by sister-in-law Kate Middleton for the women’s final.

The royal sat alongside Anna Wintour and Williams’ husband Alexis Ohanian (AFP/Getty Images)

Williams has previously said that having Markle’s support and friendship “is great,” telling reporters during her post-match press conference in July: “She’s such a great friend and a great person as well. And always positive, no matter what.”

The tennis star continued: “It’s so good to have people like that, just to know,” adding that the Duchess is “such a fan of the sport."