Siberia-born Sharapova, whose Wimbledon victory over Serena Williams in 2004, aged 17, propelled her to superstardom and riches, broke the news in an article for magazine Vanity Fair.

"I'm new to this, so please forgive me. Tennis -I'm saying goodbye," Sharapova, whose rags to riches story captivated the sporting world but turned sour when she was banned for doping, wrote in a farewell article.

Her decision to quit is hardly a major surprise as she has been a pale imitation of her former self since returning in 2017 from the 15-month ban for taking prohibited heart drug meldonium at the 2016 Australian Open.

The former world No.1 has played only two matches this year, losing in the first round of the Australian Open, with her ranking sliding to 373.

"Looking back now, I realise that tennis has been my mountain. My path has been filled with valleys and detours, but the views from its peak were incredible," she said.

"After 28 years and five grand slam titles, though, I'm ready to scale another mountain, to compete on a different type of terrain."

Sharapova, whose trademarks were her ferocious intensity and pounding groundstrokes, completed her career grand slam when she won the French Open in 2012.

She also won at Roland Garros again in 2014, her last major title.

She became the first Russian woman to reach number one in the rankings in 2005 and claimed the US Open title in 2006. She also won the Australian Open in 2008.

"It's a shame, of course, because Maria was a role model for everyone," Shamil Tarpischev, president of Russia's Tennis Federation, told RIA news agency.

"Many girls compared themselves to her. She was number one for the popularisation of Russian tennis. Her image was huge."

WTA Tour chairman Steve Simon added: "She will be greatly missed by her millions of fans around the world."

Australian Associated Press