American contender Jesse Vargas could fill the void left by Manny Pacquiao to fight Jeff Horn for the WBO welterweight title in Brisbane later this year.
Pacquiao's withdrawal from a planned November rematch was announced on Friday, due to his commitments as a Philippines senator.
The Australian defeated Pacquiao in July's "Battle of Brisbane" to snatch the world title in a famous upset.
And the second installment seemed set after the Filipino fighter's initial promise to return later this year.
But after a period of uncertainty surrounding the fight, Horn's promoter DUCO Events confirmed on Friday that a 2017 rematch was not possible.
"On behalf of the Philippines government he will be part of a delegation that will visit China in the middle of his proposed preparation period for the fight," Duco Events director Dean Lonergan said in the statement.
"Pacquiao is committed to fighting again in 2018 and a rematch with Jeff Horn for the WBO world welterweight title.
"Until then ... we will be exploring options."
The Queensland Government stated on Friday it would support Horn's title defence regardless of the opponent.
Former title-holder Vargas, who Pacquiao beat in a unanimous decision before the Horn bout, shapes as a worthy replacement.
Like Pacquiao, the Californian is in Bob Arum's Top Rank stable and his chance to retain the title could be viewed as the perfect alternative.