USA Wrestling Legend Rulon Gardner -- Furious After Wrestling DROPPED from Olympic Games

It's a DEVASTATING day for wrestling fans ... after officials announced the sport will be 86'd from the Olympics starting in 2020 ... and now one former gold medalist is lashing out.

TMZ spoke with Rulon Gardner -- who won gold in 2000 and bronze in 2004 before going on to appear on "The Biggest Loser."

Gardner tells us he's "appalled" by the International Olympic Committee's decision to drop the sport -- saying, "As a two time Olympian, I think it's a shame to drop the sport of wrestling, one of the original Olympic Sports."

Gardner says he knows there's a SLIGHT chance wrestling could be saved -- but "seeing the hardship baseball has been through, I am not too confident."

Still, Gardner says he will do everything he can to bring back the sport he loves -- "I don't think we have heard the end of this."