Playful banter between pals? After spotting Kim Kardashian’s recent Instagram post, Serena Williams is playfully offering her celebrity BFF some tennis coaching.

Kardashian shared some enticing photos from a tropical tennis court over the weekend, dressed in a pink bikini and a matching cover-up. However, a crucial detail in the snapshots revealed that this Barbie doll isn’t exactly a regular on the tennis court. The way she held her tennis racquet prop—flat and trailing behind her—was a clear giveaway for Williams and others. The 23-time Grand Slam singles champion couldn’t resist poking fun at her friend, leaving a teasing comment among the thousands flooding in.

“Definitely not the right way to hold a racquet. Looks like I need to give you some lessons lol,” Williams quipped, adding heart-eye emojis for good measure. Kardashian and Williams have shared a close friendship for many years, attending each other’s weddings and frequently appearing together at various high-profile celebrity gatherings. In July, they were spotted together at Lionel Messi’s Inter Miami CF debut.

However, the socialite may have to wait her turn, as “Coach Mama” is currently focused on training another student: her eldest daughter.

This week, Serena Williams’ husband, Alexis Ohanian, shared a picture of Alexis Olympia Ohanian Jr. practicing on a tennis court. Williams has been vocal about Olympia’s passion for tennis, and has frequently shared photos and videos on social media of the pair playing together on the court.

When former doubles world No. 1 and current coach Rennae Stubbs mentioned on Twitter that she’s “available” to take on a new pupil, Ohanian took the opportunity to highlight that Olympia is already under the guidance of a world-class mentor.