Nicola Adams' fight with Hungarian Alexandra Vlajk was called off shortly before the 2300BST start time because of a problem with her Hungarian opponent's pre-contest blood test.
The double Olympic gold medallist had been due to take on Vlajk in a junior bantamweight bout on the Canelo Alvarez vs Gennady Golovkin undercard in Las Vegas but it was called off shortly before the double Olympic champion was due in the ring.
Adams wrote on Twitter: "I'm devastated that I'm not boxing tonight, due to a problem with my opponent, thank you everyone for your support and kind messages."
