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Two of the greatest boxers of all-time have agreed to a fight ... TMZ Sports has learned Mike Tyson and Floyd Mayweather have signed a deal to square off against one another!!

We're told the match -- which will be put on by CSI Sports/Fight Sports -- is currently scheduled for sometime in the spring of 2026. Getty

An exact date and precise location are not yet known ... but nonetheless, Tyson said he's thrilled to be slated to mix it up with Floyd, whom he hasn't always had the greatest relationship.

"This fight is something neither the world nor I ever thought would or could happen," Iron Mike said. "However, boxing has entered a new era of the unpredictable -- and this fight is as unpredictable as it gets." Gallery Launch Gallery Getty

"I still can't believe Fl

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