The thought of the top men’s and women’s singles players teaming up is one that has often intrigued tennis fans around the world.

The new U.S. Open mixed doubles tournament drew plenty of criticism for everything from its format to its field. With mostly singles players, some who rarely play doubles at all, it felt less like a Grand Slam championship than an exhibition — which is what one player referred to it as Tuesday.

Defending US Open mixed doubles champions Andrea Vavassori and Sara Errani are through to the semifinals of the re-imagined format.