American boxer Hannah Rapp died on Saturday after being hit by a car while cycling in Texas.
Rapp, 26, was passed by a car which suddenly came to a stop then reversed into her, according to the Brazos County sheriff's office.
The driver has been arrested and charged with manslaughter.
Rapp challenged for the WBC women's featherweight championship in June, losing to Tiara Brown in Orlando, which left her with an 8-1-1 record.
WBC president Mauricio Sulaiman said in a statement: "She was an exceptional boxer, but above all, an invaluable member of our boxing family."