INDIAN WELLS, CA, USA - Two-time champion Maria Sharapova was forced out of the upcoming BNP Paribas Open on Wednesday due to a shoulder injury.

The Russian withdrew from the St. Petersburg Ladies' Trophy with the same injury at the end of January ahead of a second-round clash with Daria Kasatkina at that event.

The five-time Grand Slam champion has contested just three events since last summer's US Open, and has had to withdraw or retire from two of them.

The Russian reached the fourth round of the Australian Open in January before losing to Ashleigh Barty, upsetting defending champion Caroline Wozniacki along the way.

Read more: Steely Sharapova reveals pride in dethroning Wozniacki in Aussie epic

Despite having her best showing at the Australian Open since 2016, the 2008 champion was candid with her injury struggles in the Melbourne press room.

"The shoulder hasn't been much of a secret in the past year. That's been something I have been struggling with and had to shut down the season after the US Open," she revealed Down Under.

"[It's] still not where I want it to be, still working through some painful days. That's something that I have had to deal with since I was 21 years old and really at the peak of my career, [which] kind of came unexpected.

"I saw [my doctor] at the beginning of December, and he says it's a day-by-day pain management situation. It's definitely been an issue for the majority of last year and going into this year, as well, but it's something that...I'm still working through."

Sharapova won the Premier Mandatory event in 2006 and 2013, and reached the final in 2012. 

With Sharapova's withdrawal, Germany's Mona Barthel is into the main draw.