Serena Williams responded to Meghan Markle wearing a blazer from her collection in the sweetest way

The tennis champion was a guest at Markle's wedding in May

(Rex Features)

Serena Williams and Meghan Markle confirmed their allegiance to one another on Wednesday when the recently-appointed Duchess was spotted wearing a blazer from the tennis champion’s namesake fashion label.

The young royal wore the plaid oversized jacket when she was visiting university students in Dubbo, Australia as part of her official tour around the country with Prince Harry.

Expressing her gratitude on Instagram, Williams posted a photo of Markle, who was wearing the blazer over a white collared shirt and black skinny jeans, writing: “The face you make when you and Duchess of Sussex Meghan have matching @serena blazers”.

The grey “Boss Blazer”, as it’s named on the brand’s website, costs $145 (£110) and has since sold out.

The trip marks the couple’s first royal engagement since news broke that the Duchess of Sussex is pregnant with her first child, shining an even brighter spotlight on Markle and her outfit choices.

The tennis star’s label is inspired by “femininity and strength”, Williams told People earlier this year, making it a perfect fit for Markle, who is a vocal advocate of women’s rights.

The blazer worn by the Duchess is part of Serena’s “Royal” collection, which also includes a ruched pink midi dress, a tight-fitting blue midi skirt and a cropped hoodie with the words “royal” splashed across in bold red text.

It’s not the first time the Duchess’s wardrobe has caused a fashion frenzy.

Dubbed “The Meghan Effect”, Markle has been credited for sparking a number of trends in the industry, such as midi skirts and boat neckline tops, and many of the items she wears sell out within hours of her being photographed in them.

Markle’s influence is so stratospheric that there are now various websites dedicated to helping fans purchase items she has been seen wearing.

“Meghan is quickly becoming a fashion icon,” said Amanda Dishaw and Christine O’Brien Ross, editors of one such site, Meghan’s Mirror.

“Her style is modern and on-trend, while still remaining down-to-earth and relatable. People love that her style is familiar, and we could dress in similar outfits for our everyday, ‘non-royal’ lives,” they told The Independent.

“She has an extremely high profile, thanks to her new husband-to-be, and she is using that to showcase what a 21st century woman looks like.”