The greatest woman-beats-man match in sports history may have been an intricate mob ordered fraud – report.

In a historic tennis battle of the sexes that ignited the then-burgeoning feminist movement retired tennis champ Bobby Riggs lost to Billie Jean King on Sept. 20, 1973 but according to an ESPN report, the fix was in.

Playing the brash male chauvinist pig to the world’s media, Riggs, 55, lost in three straight sets to the world’s No. 2 female player of the time, King.

Yet a mere four months prior, Riggs quickly sent the then-No. 1 women’s tennis champ Margaret Court packing without breaking a sweat.

But the Billie Jean King trouncing of Riggs stunned not only the 30,472 fans at the Houston Astrodome and 50 million more watching on ABC.

But now, a country club co-worker of Riggs believes the tennis champ threw the match under “threat of death” from the mob.

Hal Shaw told ESPN OTL that Riggs was paid a midnight visit by an infamous cabal of organized crime kingpins.

Shaw clams he saw mob attorney Frank Ragano, Florida mob boss Santo Trafficante Jr. and New Orleans crime boss Carlos Marcello (cited by author John H. Davis as instrumental in the JFK assassination) enter the Palma Ceia Golf and Country Club in Tampa, Fla., club for a “rendezvous” with the tennis great.

Ragano told the criminal elite men that Riggs was going to "set up two matches … against the two best women players in the world," Shaw told ESPN.

"He mentioned Margaret Court… and the second lady was Billie Jean King,” Shaw, 79, told the sports news net.

"Mr. Ragano was emphatic … Riggs had assured him that the fix would be in — he would beat Margaret Court and then he would go in the tank" against King, but Riggs pledged he'd 'make it appear that it was on the up and up.'"

Seemingly to confirm Shaw’s claim, Bobby  Riggs’ pal Gardnar Mulloy, a tennis star of the 1940s and '50s, said Riggs told him not to wager on him to beat Billie Jean.

While Riggs was the overwhelming pick among Las Vegas bookmakers they could barely get any action going on Billie Jean, despite very long odds that would have insured a rags-to-riches payoff.

Famed Vegas handicapper Jimmy the Greek said then,  “King money is scarce. It's hard to find a bet on the girl."