Sergey Kovalev: I Fight To Honor Boxer Who Died By My Hands

Light heavyweight boxing champ Sergey Kovalev says he's driven to be a champion by the memory of Roman Simakov ... the man who died 3 days after fighting Sergey back in 2011.

We talked to Kovalev about Conor McGregor revealing he's been seriously disturbed by the fact he trained MMA fighter Charlie Ward for a match where the opposing fighter ended up dead.

That's when Kovalev opened up to us ... saying after Simakov slipped into a coma and died three days following their 2011 fight, he immediately decided to dedicate the rest of his career to his memory.

"I will be champion for me and him ... this helped me and still helps me to fight."

You gotta check out the clip -- Sergey says there's one thing he wishes and thinks about every time he steps into the ring.