Brett Morris and Jarryd Hayne scored four tries each as Australia reached the Rugby League World Cup last four with an easy victory over the USA.
But the win was overshadowed by an injury to full-back Billy Slater who had to leave the field in the second half after aggravating a knee problem.
Morris and Hayne are the fifth and sixth Australians to score four tries in a World Cup game.
Greg Inglis added two tries and Cameron Smith and Cooper Cronk also crossed.
Hayne got his side off to the perfect start within the opening three minutes.
The Kangaroos played the ball across the line, and Slater and Inglis got the ball out to the centre, who made no mistake - though Johnathan Thurston missed the kick, in what was a mixed performance by his high standards.
The USA defence was under constant pressure and it was no surprise when Inglis powered over on 11 minutes.
In total control, the Kangaroos then went over for three quickfire tries.
First Morris shrugged off the attentions of the Tomahawks defence for his opener and then captain Smith got a piece of the action after Paul Gallen's neat off-load. When the Kangaroos again swept down the field, an inside pass by Slater found Morris for his second try of the game.
Morris completed his hat-trick on 35 minutes with Inglis again the provider, after the ball was spread across the field from an Australian scrum 20 metres from the line.
Morris made it four just on half-time when a beautiful high looping kick from the boot of Cronk found him on the wing and he leaped above the USA's Matt Petersen.
But two minutes after the restart, Slater had to be helped off the field, when he was tackled after taking a high ball.
Australia coach Tim Sheens confirmed that the 30-year-old had suffered a recurrence of a posterior cruciate ligament injury, which ruled him out for several weeks last year.
Slater will undergo and MRI scan on Saturday night but Sheens has not ruled the Melbourne player out of the tournament although he will miss next Saturday's semi-final against either Fiji or Samoa.
"It's an injury to his old injury - PCL," said Sheens. "It's just what damage may have been done, cartilage and other things. We're just hoping it's a bad knock but we're sending him for an MRI.
"We've still not given up the thought that he might possibly be available, probably not this week after that sort of knock, the week after if we get that far.
"I'm not going to panic just yet until we get (the results of the MRI). The issue is the knock and how much damage it's done."
The USA tried to find gaps in the Kangaroos defence but Tim Sheens' side thwarted their opponents and on the attack they continued to look dangerous.
On 50 minutes, Inglis bullied his way through the Tomahawks defence for his second try.
Hayne then became the principal danger man in the latter stages with three further tries, helped by both Morris and Inglis to set up a semi-final meeting against Fiji or Samoa at Wembley next Saturday.