SYDNEY, Australia - As previously reported on BoxingScene.com, WBO welterweight champion Jeff Horn's title defence in Las Vegas next month has been postponed after mandatory challenger Terence Crawford injured his hand while sparring, organizers said Thursday.

The Australian was due to fight the undefeated Crawford on April 14 at the Mandalay Bay Events Center in Las Vegas, but it has now been put back to a yet-to-be-decided date.

"Jeff Horn's scheduled world title defence against highly-rated American Terence Crawford has been postponed," Horn's team said in a statement. "Crawford suffered an injury to his right hand in a sparring session and a rescheduled date is yet to be determined."

Horn, who upset eight division world champion Manny Pacquiao to take the World Boxing Organisation title last July, said he was disappointed and cast doubt of the seriousness of the injury.

"Hopefully it's an injury he's had to postpone it for and not a tactic to throw us off our game," Horn said.

"The Americans are saying he's such a great fighter, why doesn't he fight with one hand then."

Horn is not alone in doubting the severity of the injury, as Crawford's hand issue was revealed only hours prior to an internal ESPN announcement that Crawford-Horn would be exclusively streamed on a brand new ESPN app that is set to launch in the coming months.

After Horn pulled off his shocker over Pacquiao, there was a rematch in discussions for last November, but the Filipino veteran withdrew after citing scheduling conflicts with his work as a senator in the Philippines.

Horn would instead defend his title in December with an 11th-round stoppage of England's Gary Corcoran.

Crawford is unbeaten in 32 bouts and will move up from the junior welterweight division to welterweight to challenge the Australian. Crawford also held a world title at the lightweight limit of 135.

The fight is now being targeted for mid-May or a date sometime in June.