Four months after being first mooted, Jeff Horn's US boxing debut has finally been locked in.
Official confirmation arrived on Friday for Horn's second WBO welterweight title defence against Terence Crawford on April 14 in Las Vegas.
"I'm really happy it's done," Horn's promoter, Duco Events boss Dean Lonergan, told AAP.
"We've got execution copies (of the contract) right now in front of Glenn (Rushton) and Jeff to sign.
"This is the most significant fight, I think, in the history of Australian boxing.
"When was the last time an Australian boxer came up against an all-time legend in Manny Pacquiao and, less than a year later, fight the pound-for-pound king?"
Lonergan said the long delay was simply because Bob Arum's US promotions company Top Rank were busy and only managed to send the first draft of the contract two weeks ago.
Top Rank have a co-promotional deal with Horn that expires after this fight.
"Would I have liked to have gotten this contact finished sooner? - 100 per cent but, at the end of the day, you can only work with what you're given," he said.
Horn's camp will welcome the certainty, as well as two major clauses around judges and drug testing.
It ensures the three-judge panel at the 12,000-seat Mandalay Bay Events Centre will include one Australian, one European and one Nevada local - as Horn's trainer Rushton had insisted on.
Lonergan was hopeful the respected Kenny Bayless, who oversaw Pacquiao's megafight with Floyd Mayweather in 2015, or Tony Weeks would be assigned as referee.
Both fighters have also agreed to two mandatory blood and urine tests before and after the fight.
"We just wanted to make sure we're on a level playing field here," Lonergan said.
"The great thing about Terence Crawford was his attitude was he doesn't care how many times he gets tested.
"We know we've got two clean fighters going into the ring and we're going to have a great fight."
Crawford, who is unbeaten in 32 fights after unifying the super lightweight division, is heavily favoured to win but Lonergan says Horn is ready to shock the world again.
"Crawford's got great technical ability, there's no doubt about that, and he's a hell of a fighter," he said.
"But I think there's enough chinks in the Crawford armour - and no doubt, he thinks the same about Jeff.
"We think he can beat Crawford. And not beat him just - beat him well.
"Crawford should bring his suit of armour because it's going to be another bloody, hard war."