Top Rank’s Mikaela Mayer tests positive for COVID-19, is out of boxing’s return to ESPN on Tuesday

Mikaela Mayer, the unbeaten 2016 U.S. Olympian, announced Sunday on social media that she is off of Top Rank’s show Tuesday that represents the return to boxing because she tested positive for COVID-19. Mayer said in a post on Instagram that she tested positive on Saturday when she arrived at the MGM for her fight against Helen Joseph. Tuesday’s card will be the first Top Rank has staged since the heavyweight title bout between Tyson Fury and…