The US boxing debut of undefeated Australian superstar Tim Tszyu has been thrown into doubt following a training injury to his potential world title rival.

Tim Tszyu's much-anticipated US boxing debut is up in the air following a training injury to one of card's headline acts.

Tszyu was scheduled to place his undefeated record on the line against Terrell Gausha as the co-main event on March 19 in Los Angeles.

But the Australian superstar admits he's now "in limbo" after Brian Castano suffered a bicep injury.

The Argentine was meant to face American Jermell Charlo in a long-awaited unification bout serving as the co-main event alongside Tszyu's fight with Gausha.

As the mandatory challenger to Castano's WBO belt, Tszyu was in line to fight the winner of the unification tussle that's been more than a year in the making.

But WBO president Paco Valcarcel said Castano and Cherlo won't be fighting as planned - at least not on March 19.

That was news to Tszyu and his manager Glen Jennings, who said he was largely in the dark.

"Whether or not it gets moved, no one really knows just yet. There's not a lot of information unfortunately," Jennings told AAP on Thursday.

"You would think it's off, but how would you know with these guys? They have a few cards up their sleeve.

"They could certainly put on another card. It's just the unknown for us.

"So, at this point, the best thing we can do is carry on with business as usual until we get any other concrete ruling.

"But, right now, our fight is still in good shape. It's not our fault that one of the main event guys got hurt."

While continuing with his training camp on the Gold Coast, Tszyu conceded Castano's injury was a setback.

"It's disappointing but injuries happen and I'm in limbo right now," he said.

"We're just waiting on further information to determine how we move forward."