'Many people jealous'

"It was a pleasure to share the court with you @MariaSharapova. We always had great battles when we played and I have so much respect for your hard work and the way you always fight for everything," tweeted the Czech.

"You have achieved a lot in your life so far and I know this is just the start."

Men's world No 6 Stefanos Tsitsipas, who was only five when Sharapova won Wimbledon in 2004, said many of the Russian's rivals can only be envious of her success.

"I think many people are jealous of the career that she had," said the Greek, also playing in Dubai this week.

"Obviously she was behind Serena, another great athlete. I would say after Serena she's probably the best after her.

"She had a really good career with great victories, great achievements in tennis. I think she added a lot to our sport."

WTA chief executive Steve Simon added: "She will be greatly missed by her millions of fans around the world, but I know this will also mark an exciting new beginning for Maria as she now focuses on her many business ventures, charitable activities and other outside interests."

Sharapova's coach, Riccardo Piatti, tweeted: "It's been an honor to have worked with such an amazing athlete and person. I'll miss her on court and outside."

Olympic champion Monica Puig praised Sharapova for helping in relief efforts when Puerto Rico was devastated by a hurricane in 2017.

"Thanks for being such a great friend and a true example of what a champion really is. I wish you nothing but the best. You deserve it," she tweeted.

AGENCE FRANCE-PRESSE