Sam Kerr came off the bench as Australia surged into the Women's World Cup quarterfinals with a win over Denmark in front of nearly 76 000 fans in Sydney on Monday.

The co-hosts will play France or Morocco on Saturday in Brisbane after making fairly light work of a toothless Denmark.

To cap a good night's work for the Matildas, talismanic striker and captain Kerr came on with 10 minutes left to huge cheers for her first action of the tournament after a calf injury.

The dangerous Caitlin Foord ran Denmark ragged throughout and scored a fine first goal after being set up by the impressive Mary Fowler on 29 minutes.

Hayley Raso grabbed a second to make the game safe 20 minutes from time.

The Chelsea predator Kerr, who was supposed to have been the face of the World Cup before injury struck on the eve of the tournament, said it was "a big relief to be back".

"I feel good. I think I was a bit rusty but, no, I feel great.

"I'll sleep better tonight than I have for the last three weeks."

The home side are thriving on growing excitement at what they can achieve at this World Cup, where holders the United States are out, opening the door for a new champion.

"I think we're embracing it, I think the girls are loving it," Kerr said of the expectation.

"The Australian public has been amazing. We’ve felt the love, just walking down the street it's been a real buzz."

‘PRETTY SCARY’

Denmark were contesting their first knockout game at the World Cup since 1995 and they had the first sniff of goal, but Rikke Madsen just failed to connect with the ball while sliding in at goal.

The Danes, ranked 13th in the world to Australia's 10, could have taken the lead on the quarter-hour at Stadium Australia but Pernille Harder shot straight at goalkeeper Mackenzie Arnold.

Australia were on the back foot early but took the lead against the run of play when Fowler threaded a superb long pass down the left to play in Foord.

The Arsenal forward still had plenty to do and she did it brilliantly, taking one touch with her right foot to guide the ball into her path and then firing with the left through the legs of goalkeeper Lene Christensen.

Foord was all over the Denmark defence with her pace and movement down the left.

Minutes later she rampaged down the wing again, chopped back inside and let fly with her right foot, the ball taking a big deflection and whistling just beyond the top corner.

Into the second half and Foord seemed to be everywhere, sliding in to stop a Denmark counter-attack and earning vigorous applause from Australia's coach Tony Gustavsson.

Defender Janni Thomsen decided she had had enough of Foord and was booked for crudely pulling her down as she arrowed towards the Danish box.

The crowd sensed a second could be coming and it duly did, Fowler again playing a key part to set up Emily van Egmond, who teed up Raso to fire into the bottom corner.

But the biggest cheer of the night was yet to come as Kerr belatedly came to the World Cup party as a substitute.

Foord called Kerr's return "a massive boost for us".

"For (other) teams looking ahead it's pretty scary to know that she's back in the team and she's going to be a part of it with us," she said.

Foord called the heaving Stadium Australia crowd "our 12th man" and Gustavsson said of the support: "I get emotional, I really do.

"The support – we feel it, thank you. Wow."