The Fiji Rugby Union has officially confirmed this.
This unfortunate setback means that he will be unable to participate any further in the tournament
Teti Tela is set to step in and take the field against Wales on Monday.
Muntz, who made his debut for Fiji earlier this year, had been in exceptional form and played a pivotal role in Fiji’s impressive 30-22 victory over England just two weeks ago.
Coach Simon Raiwalui said its most devastating for them as a group and for Muntz.