The fighting world is rallying around Francis Ngannou following the death of his son ... with many combat sports stars -- including Manny Pacquiao and Anthony Joshua -- sending their prayers and condolences his way on Monday.
The heartfelt notes were left on Ngannou's Instagram page ... in the comment section of a post where the former UFC champ mourned the loss of Kobe, his 15-month-old son.
"How do you deal with such a thing?" Ngannou said in the post. "How can you live with it?"
"Please help me if you have an idea because I really don't know what to do and how to deal with this."
Thousands of fans and fighters came to his aid ... with Pacquiao saying he can't imagine the "pain and struggle" Ngannou's going through right now. Joshua added, "May the memories you shared bring you comfort 🙏🏾".
Former UFC champ Henry Cejudo also sent his sympathy ... saying, "I’m so sorry for your loss Francis. Losing family is the hardest thing a human can go through in life. We don’t have the answer but one day you’ll meet again. We love you my brother ❤️."
Derek Brunson, Roy Nelson, Dillon Danis and other MMA fighters shared their love too.
Even athletes outside the fight world sent prayers, with NHL star Evander Kane and NBA forward Thanasis Antetokounmpo leaving messages as well.
A cause of death for the child, meanwhile, has not yet been revealed.
RIP.