According to TMZ Sports, former three division world champion 'Sugar' Shane Mosley has filed a lawsuit with claims that a simple surgery to correct an elbow injury was allegedly botched and eventually ended his career.

Mosley claims he was training for a fight in March 2017, when he went to Dr. Gary Brazina about pain and clicking in his right elbow.

He says the doctor suggested arthroscopic surgery to fix it, and explained it would be relatively quick and painless, with plenty of time to recover for his fight.

According to the legal documents ... it didn't go as planned at all.

Mosley says the surgery took hours longer than he was told, and Brazina revealed he had to "detach some ligaments and reattach them with screws."

Mosley claims he developed a fever and rash the next day, and Brazina failed to tell him he also suffered a severe burn during his surgery ... which became infected.

What's worse -- the boxer claims his doctor altered some pre-op paperwork to make it appear like Mosley consented to a more invasive surgery than he did.

He's suing Brazina and the hospital where his surgery was performed for damages. 

Mosley advised BoxingScene.com in August of 2017, that he never planned to retire from the sport - at least at that point - but the surgery ended his career.

"I had a few more years left in me and had a few big fights lined up for 2017 and 2018. [Bernard] Hopkins fought up to 50 at the world class level and he has always been a role model and friend. However, fate if you will stepped in and took those options away from me earlier this year," Mosley detailed to BoxingScene.com.

"I went in for a minor arthroscopic surgery to remove a couple of loose bone fragments from my elbow and the surgery turned into a whole ordeal after the surgeon admittedly... accidentally burned me on my forearm leading to me getting a sick infection and needing like 4 or 5 days of IV antibiotics and two weeks of antibiotics at home. It was crazy and surreal to learn that I could never fight again."

"I still can’t even straighten my arm or bend my arm to this day and have numbness in my fingers. It’s really sad and I have been dealing with some depression over losing something that was this important to me. I have been in physical therapy since it happened."