Clijsters, former world number 1, on the Rybakina case: "It doesn't look good".

Elena Rybakina has many people worried.

Forfeited for the Seoul tournament and already forced to withdraw from the second round of the US Open, all without giving any reason, the Kazakh's physical and psychological state is raising questions.

There are even rumours of a form of depression caused in particular by the separation from her long-time coach, Stefano Vukov.

Following in the footsteps of Andy Roddick, who had already expressed concern for the world No. 4, retired tennis star Kim Clijsters declared: "I think there's certainly more to find out.

He (Vukov) was at the US Open. He had accreditation. He was there.

It's a bit strange... Nobody knows more, except perhaps certain members of the organization.

I think we'll know more in the future.

But, right now, it doesn't look good..."