Originally published on ProWrestlingSheet.

WWE Legend Bret Hart just revealed he's been diagnosed with prostate cancer ... but the Hall of Fame wrestler assures his fans that he won't let it take him down without a fight.

Hart made the announcement on Instagram and explained, "I now face my toughest battle. With hesitation and fear, I openly declare myself in my fight against prostate cancer. In the next few days, I will undergo surgery with the hope of defeating this nemesis once and for all."

The Hitman says, "I beat the odds when I suffered my stroke in 2002, but it is now yet again, that I ... stand unafraid and face the tough road ahead of me, I will march toward this destiny with his spirit chanting in my ear."

No word on how long he's been fighting -- but last month Bret's brother Smith Hart announced that he also has prostate cancer.

Bret Hart adds, "I refuse to lose, I will never give in or give up, and I will win this battle or die trying."