Oscar De La Hoya tells TMZ Sports ... Conor McGregor won't connect ONE SINGLE SHOT during his fight with Floyd Mayweather

Not one.

He's serious.

Oscar has been a loud opponent of the fight from the start -- saying boxing fans should focus on world-class matchups like Canelo vs. GGG and Miguel Cotto vs. Yoshihiro Kamegai.

But get this, despite his war of words with Dana White -- ya know, when Dana cussed him out -- Oscar says the two have buried the hatchet. "That's my man. There's no tension whatsoever."

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