Penrith Panthers forward Reagan Campbell-Gillard has been called into Australia's World Cup squad following the shock withdrawal of Andrew Fifita.
Fifita was named in the Kangaroos' 24-man squad just 48 hours ago but rang coach Mal Meninga to express his desire to represent Tonga instead.
"Andrew called me and said he was passionate about playing for Tonga and I respect and support that decision," Meninga said. "It is obviously a significant boost for Tonga as well as the World Cup - and international rugby league in general.
"At the same time it is also a great opportunity for someone like Reagan, who has been outstanding for the Panthers. I'm extremely excited about seeing Reagan in a Kangaroos jersey."
Australia play England in the opening game in Melbourne on October 27.
New Zealand have been dealt a similar blow with Jason Taumalolo announcing he, too, will be playing in the World Cup for Tonga, who face Scotland in their opening group game on October 29.
Campbell-Gillard's Panthers' teammate Josh Mansour has also been drafted in as a late replacement.
Mansour, who tore his anterior cruciate ligament in a training mishap during last year's Four Nations series in England, gets his chance following the withdrawal of Darius Boyd, who has failed to recover from a hamstring injury.