Maria Sharapova is set to make a "major announcement" here tomorrow ©Getty Images

Russia's five-time Grand Slam winning tennis champion Maria Sharapova is set to make a “major announcement" on her future here tomorrow.

Her agent Max Eisenbud refused to say what the announcement will be about when revealing it today.

But it has led to growing speculation that she may be about to announce her retirement.

This comes after Sharapova withdrew from the BNP Paribas Open starting next week in Indian Wells due to a left forearm injury.

The 28-year-old, currently ranked seventh in the world, has struggled with a string of injuries in recent months and has not competed since she lost to American rival Serena Williams in the quarter-finals of the Australian Open in January.

She has only played three events in the last eight months.

It is possible the announcement could relate to one of the Los Angeles-based Russian's growing business projects, although such developments are not usually billed this way.

Maria Sharapova, pictured arriving at the Vanity Fair Oscar Party here last week, has been spending more time on business ventures away from tennis in recent months ©Getty Images
Maria Sharapova, pictured arriving at the Vanity Fair Oscar Party here last week, has been spending more time on business ventures away from tennis in recent months ©Getty Images

If the speculation is true, however, the news would be a major shock for the tennis world, depriving it of one of its biggest names.

Sharapova, who was born in Nyagan but grew up in Sochi before moving to Florida to train at the Nick Bollettieri Tennis Academy, broke through aged 17 in 2004 to become third-youngest woman to win the Wimbledon singles title, behind only Lottie Dod and Martina Hingis. 

A 10-time Grand Slam finalist, she won the 2006 US Open, the 2008 Australian Open and both the 2012 and 2014 French Opens, making her just the 10th women to secure a career Grand Slam.

She won a silver medal on her first Olympic appearence at London 2012 after becoming the first Russian woman to carry her country's flag at an Olympic Opening Ceremony.

Maria Sharapova carried the Russian flag at the London 2012 Opening Ceremony ©Getty Images
Maria Sharapova carried the Russian flag at the London 2012 Opening Ceremony ©Getty Images

She also returned to the town she grew up in to appear as a Samsung ambassador at the Sochi 2014 Winter Olympics.

Sharapova has spoken positively about competing in August's Olympic Games in Rio de Janeiro, although she had been warned by Russian tennis boss and International Olympic Committee member Shamil Tarpishchev that her withdrawal from the Russian Fed Cup team for a match last month risked her Olympic selection.

The "major annoucement" is set to be made at a news conference scheduled for 12pm local time here tomorrow.