US star Gaethje wins at Trump's UFC White House show

Justin Gaethje provided the perfect ending for American fans at the White House as he shocked Ilia Topuria to win the UFC undisputed lightweight title.

American Gaethje, 37, shrugged off his underdog tag as he stopped Topuria at the end of the fourth round to become undisputed champion for the first time.

Gaethje hurt Topuria multiple times in a brutal contest as the Georgian-Spaniard retired on his stool before the fifth round for the first defeat of his 18-fight career.

The one-of-a-kind show, billed as UFC Freedom 250, took place on US President Donald Trump's 80th birthday as part of celebrations to mark 250 years of American independence.

After securing victory, which UFC commentator Joe Rogan called "one of the biggest upsets in the history of the sport", Gaethje did his signature backflip from the top of the cage before shaking hands with Trump.

In a rousing post-fight interview, Gaethje compared his underdog status to Americans who once fought for their country's independence.

"I'm from America, 250 years ago we were way bigger than 6-1 dogs, and look at us thriving now," said Gaethje.

"To all the current, former and future military service members, thank you so much."