DOHA: Australia's Mathew Leckie described his intense emotions after scoring in a 1-0 win over Denmark that took the Socceroos to the last 16 of the World Cup for the first time since 2006.

Leckie struck on the hour mark with a twisty run and low finish to ensure Australia finished second in Group D behind world champions France and knocked out the fancied Danes.

"I think in those moments you don't think too much, you don't have time to think, you know it all happened so fast. It was a great ball and I had one more man to beat," said Leckie of his goal.

"Low and hard, it's difficult for a keeper to save and as I soon as I saw it was going in I was so excited and so happy.

"I think by the celebration you can see how much emotion there was. I'm just so proud you know, we've worked so hard.... My first World Cup is probably one of the most important goals for me and for the team."

Australia will now face the winners of Group C, which will be decided later on Wednesday.