Maria Sharapova, a five-time Grand Slam winner, retires at age 32

On Instagram, accompanying a photo of her as a young child on the tennis court, she added: 'Tennis showed me the world — and it showed me what I was made of.

'It's how I tested myself and how I measured my growth.'

'And so in whatever I might choose for my next chapter, my next mountain, I'll still be pushing. I'll still be climbing. I'll still be growing.'