Claressa Shields became the first-ever U.S. boxer to win back-to-back gold medals, dominating Netherlands fighter Nouchka Fontijn in the women’s 75 kg final on Sunday.

Shields won by unanimous decision, showing the kind of speed and power that has made her the pound-for-pound best female fighter in the world over the past four years.

“I did it,” Shields said on NBC’s telecast after the fight. “I wanted it to be known that I’m not just a great female boxer. I’m one of the greatest boxers to ever live.”

She celebrated with a cartwheel.

The 21-year-old Shields improved her record to 77-1 and is the first fighter, male or female, to win consecutive Olympic gold medals. Only former U.S. boxer Oliver Kirk has won two Olympic titles – he won a gold as a bantamweight and featherweight in 1904.

Shields, who hasn’t lost a fight in over four years, also won a gold medal as a middleweight during the 2012 Olympics in London.