Katie Taylor was being lined up to become the first female boxer to headline at Madison Square Garden against Amanda Serrano in April is off postponed because of the coronavirus crisis.
Ireland's Taylor was set to defend her world titles against the Puerto Rican in Manchester on 2 May.
"To all my fans that keep asking me - Yes, my May 2nd fight has been postponed, a new date to be announced soon," Serrano said on Twitter.
There has been no confirmation from Taylor or promoter Eddie Hearn.
"It has nothing to do with myself or my opponent. Everyone knows the critical crisis we are in," added the 31-year-old, who has won world titles in seven weight divisions.
"This Covid-19 is serious. Please be safe out there. God bless us all."
Serrano boasts a record of 27 knockouts in 37 pro fights, tasting defeat on just one occasion.
The 31-year-old has collected more titles in weight divisions – seven - than any other female in boxing history.
The American is contractually bound to face Taylor next under the terms of her three-fight co-promotional deal with Taylor promoter Eddie Hearn and Lou di Bella but has been holding out for an improved purse before agreeing to a date.
Earlier this month Taylor's manager Brian Peters said Serrano, Cecilia Brækhus and a rematch with Delfine Persoon were the priority for 2020 and if all three fights could be made, it would set up Taylor’s schedule for the year.
Hearn has reiterated that idea and revealed he is attempting to make Serrano the first of those bouts in a historic event.
With Persoon signalling her intention to represent Belgium in the Olympics next summer, Serrano has been eyed up as the first opponent.
Hearn told iFL TV: "My aim for Katie Taylor is for her to become one of the biggest stars in sport. Forget female or male, just a star of the sport, to give her the credibility, and get her the money that would be ground-breaking in the sport and (an amount) I want her to walk away with.