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Claressa "T-Rex" Shields of Flint made history Sunday in Rio by becoming the first American boxer to ever win back-to-back gold medals at the Olympics. She won her first in 2012 in London at age 17.

ESPN's Dan Rafael writes that Shields, 21, dominated on Sunday against Nouchka Fontijn of the Netherlands, winning all four rounds on all three judges' scorecards. 

"I wanted to let everyone know that I'm not just a great female boxer but I'm one of the greatest boxers to ever live," an overjoyed Shields said after the bout, ESPN reports. 

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Read more: ESPN