Andy Ruiz Jr. could lose one of his four world titles before he even has the chance to defend it, SportsMail reports.
The Mexican boxer shocked the world by beating Anthony Joshua on Saturday night, knocking the Brit down four times before forcing a seventh-round stoppage.
Doing so made him become the WBA, WBO, IBO, and IBF defending heavyweight champion.
A rematch has already been penciled down for the end of the year in the UK, but all four belts may not be on the line.
One of the four sanctioning bodies, the IBF could call on Ruiz to defend their belt against mandatory challenger, Kubrat Pulev.
The 29-year-old may however decline in favour of another big money showdown with Joshua, meaning that he would be stripped of the title.