American boxer Mikaela Mayer’s fight this week in Las Vegas has been cancelled after she tested positive for coronavirus.

The undefeated Olympian was set to feature on the undercard of promoter Bob Arum’s first show back on ESPN since the pandemic, which will be headlined by Shakur Stevenson v Felix Caraballo.

But the California-born super featherweight will now have to wait for her 13th professional fight as she looks to maintain her perfect record.

Speaking about having to pull out, she said: "I am heartbroken to report that I will no longer be fighting on Tuesday’s Top Rank card due to a positive result in my COVID-19 test yesterday.

"It came as a complete surprise. I am currently asymptomatic and am quarantining at an off-site location per recommended guidelines.

"The rest of my team tested negative and they are all in good health. I was really looking forward to bringing back boxing for all of you and I’m disappointed for myself, my team, my supporters and for my opponent, Helen Joseph, who worked just as hard to be here this week and put on a show for everyone.

"After two hard back-to-back camps, not being able to step in to the ring both times, you can imagine how disappointed I am. However, these protocols were put into place for a reason and it's more important to care about the health and wellbeing of my team and the people at this event. So I am complying with the rules set forth by the Nevada State Athletic Commission and Top Rank to keep everyone safe.

"I will just have to take a quick break but I will be in the ring soon. I appreciate all the love and support. Please tune in to ESPN on Tuesday night and support the card and all of the fighters. Boxing is back and I'll be back. #boxing."

Mayer has not boxed since October last year when she stopped Alejandra Soledad Zamora in six rounds in Reno.

She has recently sparked a feud on social media with British WBC champion Terri Harper, accusing her of ’buying’ her world title.

However, Harper’s next defence has already been decided and will be against fellow countrywoman Natasha Jonas.