South Sydney's Luke Keary and Manly's David Williams face extended periods on the sideline after the Auckland Nines claimed some big-name casualties on day two of the tournament.

There are fears Williams will join Cowboys fullback Lachlan Coote as the second player to suffer an anterior cruciate ligament injury at the tournament, while Keary's shoulder injury could put him out for three months.

Keary's injury has thrown Michael Maguire's plans to start the year with a new-look halves combination into disarray, leaving the Rabbitohs coach on the search for a halves partner for Adam Reynolds. The full extent of the injury Keary suffered in the pool match against Penrith will be determined on Monday, but it is understood the playmaker will not be fit to start the year.

Knights five-eighth Jarrod Mullen (hamstring), David Stagg (knee), Dave Taylor (leg), Todd Carney (hamstring) and Coote (knee) were some of the biggest names to leave the tournament worse for wear.

The injury to Keary is a huge blow for South Sydney, who have trained all pre-season with him in the halves alongside Reynolds and skipper John Sutton in the forwards. "Unfortunately he has something in there with his shoulder so we're not 100 per cent sure exactly what it is yet," Maguire said. "He has had a great pre-season and that's the unfortunate thing. We just have to move forward. Hopefully we get a bit of good news from the doc. He said it's not looking great at the moment so we have to see what the scan shows."

Sutton has spent the past two years in the No.6 jersey, but Maguire insists he isn't his only option. "I have learnt I have to cover a fair few things," he said. "We have other options there with Dylan Walker. With Lote [Tuqiri] and Joel Reddy coming in, it gives us some options in the outside backs. We'll go away and see how his injury is and from there assess him. Sutto has been doing a great job in the middle so we will wait and see what happens. It is really disappointing for everyone. [Luke] is a great kid. He is going to bounce back. It's an unfortunate part of a footballer's career that these things happen. It's really sad for Luke."

Keary suffered the injury trying to stop a Panthers try, instead had his arm pushed back behind his body. "I'm very disappointed he got injured," Sutton said. "He trained the house down all pre-season and was one of our best players this tournament.

I don't know how serious of an injury it is but hopefully it is not too bad."