Jarrod Mullen, Luke Keary and David Stagg all joined the early season casualty list at the NRL Nines on Sunday.

As the inaugural competition at a sold out Eden Park continued into its second day, the injury toll mounted after some significant injuries on the opening Saturday.

Brisbane utility Stagg will be sidelined for up to six weeks with a medial ligament injury, while Newcastle playmaker Mullen (hamstring) and South Sydney young gun Keary (shoulder) are both in doubt for the opening round of the NRL in two weeks.

Mullen and Keary will have scans on their injuries when they return to Australia.

The Broncos confirmed Stagg, who suffered the injury in the Broncos quarter-final win over Newcastle, faces six weeks out.

A number of players suffered serious injuries on the opening day.

North Queensland fullback Lachlan Coote will miss at least six months after rupturing his ACL, Wests Tigers utility Curtis Sironen will be sidelined for six weeks with a foot injury and Cronulla five-eighth Todd Carney is in doubt for the Sharks round one clash with the Gold Coast with a hamstring injury.

Manly pair David Williams (knee) and back-rower Michael Chee-Kam (elbow) also failed to finish the tournament, while Penrith youngster George Jennings suffered an elbow injury.