Mickey Rourke's Opponent -- I DIDN'T THROW THE FIGHT ... I Only Trained For a Month

Mickey Rourke's 29-year-old opponent Elliott Seymour is adamant he wasn't paid to take a dive in their big boxing match in Russia this weekend .. telling TMZ Sports Mickey beat him fair and square.

Almost everyone who's seen the fight has called BS on the "knockout" ... with Seymour going down for the count in the 2nd round after a weak ass body shot from the 62-year-old.

But Seymour -- who returned to L.A. after the Crumble in the Kremlin -- says, "The fight wasn't thrown. I only had one month to train."

Seymour confirmed reports that he's struggling financially and has been living on the streets -- but says he was paid to fight ... not to lose.

When asked how much cash he made from the bout, Seymour pointed to a photo of $100 bills on a bed ... and suggested that was his purse. It looks like $3,000 to us.

We also asked if he's planning to fight again to which he replied, "Who knows? I’m keeping an open mind."