(CNN) Not so fast, Usain Bolt -- there's a new World Championships record holder, and her name is Allyson Felix.

USA Olympic sprinter Felix broke Bolt's record Sunday after winning her 12th gold medal at the World Championships on the mixed-gender 4x400m relay team. She now holds the record for the most gold medals at the track and field World Championships.

DOHA, QATAR - SEPTEMBER 29: Allyson Felix of the United States reacts after setting a new world record in the 4x400 Metres Mixed Relay during day three of 17th IAAF World Athletics Championships Doha 2019 at Khalifa International Stadium on September 29, 2019 in Doha, Qatar. (Photo by Patrick Smith/Getty Images)

Felix is already one of the most decorated track and field athletes, winning a combined nine medals between each of her four Olympic games. Six of the medals are gold.

Felix summed up her response to the honor in one word on Twitter: "Humbled."

Another big accomplishment for Felix, it's her first season as a mother. But her journey back to the track has not been an easy one.

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