The same knee injury that kept Billy Slater sidelined for six weeks is expected to end his World Cup campaign after he limped from the field during Australia's 62-0 win against the USA.

Slater missed last year's Origin III and six club games after straining his posterior cruciate ligament. The left knee was too swollen for results to be conclusive when the fullback was taken for scans following Australia's win.

However, Slater feared the worse when he was taken from the field early in the second half.

''It's a bit sore,'' Slater said. ''There's not much I can do about it. I'll get scans and we'll know more from there. It's the leg that I did in the second State of Origin last year. It seems like the same injury. I suppose that's a good thing because the PCL isn't functional anyways.

''I suppose the only concern is the cartilage now and we'll know more from the scans. It's a classic PCL injury. There's a lot of swelling in the knee. Hopefully we can get some swelling out.''

It was a grade three PCL that sidelined Slater for an extended period last year. Slater's PCL is non-functioning and players can play on without it but he remained in discomfort post-match.

''I knew straight away what it felt like,'' Slater said. ''Hopefully the scans came up good and I'm a chance of playing again in the tournament. That remains to be seen.

''I actually have [a PCL] but it's torn and the knee was loose anyway. It's hard for me to put a timeframe on it. I'm pretty sure if the scans come back bad it'll be the tournament over for me. Hopefully I'm a chance of playing again.''

The injury capped a turbulent week for Slater, who was involved in a nightclub scuffle in Manchester. Slater said he has ''tried to put all that behind me''.

His likely replacement Greg Inglis scored two tries in his best performance of the tournament. Inglis roamed around the field with the ball more against the Tomahawks as he looked to get more involvement.

Inglis played his first game for Australia at fullback in the Kangaroos' 34-2 win over Fiji in the pool stages.

''I would love to wear that No.1 but I am not the coach,'' Inglis said. ''The first game I was a bit quiet so I put it into my head that I had to touch the ball a bit more.

''Hopefully the scans come back all clear. In the end [Slater] is a valuable member to this team. To see him go down like that was disappointing but like I said hopefully we see the scans come back all clear.

''I just want to get my hands on the ball and run a bit more.''