Roddick on Rybakina: "Like a feeling of bad news".

Elena Rybakina's situation is worrying.

Promised a radiant future, the Kazakh has suffered one physical setback after another, as evidenced by her withdrawal from the second round of the US Open, her eighth of the season.

Stranger still: the world number 4 refused to give the reason for her decision to retire.

Rumours of depression are circulating in the tennis world, potentially caused by the end of her tormented collaboration with her coach, Stefano Vukov.

Commenting on Rybakina's situation, Andy Roddick admitted he was worried: "There's a sense of impending bad news.

I'd like to be wrong. It's pure speculation. It's just a question out loud, I don't know.

What I do know is that she's an elite player when she's ready, happy and focused. For me, the best waitress on the women's tour.

Her game is very fluid, especially for her size, with movement.

I hope she finds her happiness and health on the court as soon as possible."