The Socceroos have given their hopes of qualifying for the World Cup last 16 a tremendous boost with a tense, battling 1-0 victory over Tunisia.

Mitch Duke's superb first-half header was the only goal of a hard-fought game, despite Tunisia laying siege to Australia's goal late in the second term.

However, the excellent Harry Souttar made a number of telling tackles and Mat Ryan some solid saves to preserve a rare clean sheet, Australia's first at a men's World Cup since 1974. 

The Socceroos made just one change, with Nathaniel Atkinson, who was given such a torrid time by Kylian Mbappé in the opening game, missing out with an ankle injury.

Atkinson was replaced in the line-up by Fran Karačić.

Graham Arnold had warned that Tunisia would prove to be physical opposition and that proved to be the case, with the midfield skirmishes particularly intense from the off.

The Socceroos met that aggression head on, matching that physicality and unsettling the Tunisian players, who turned the ball over with alarming regularity in the opening exchanges.

That intensity created a scrappy and awkward opening 20 minutes, during which the Socceroos steadily gained the upper hand, playing most of the game in Tunisia's half. 

It took time for Australia to create any real openings though, Tunisia's defence handling the Socceroos' crosses as Australia looked to work the channels and get Craig Goodwin into the game on the left.

It was through that route that Australia scored the opener thanks to a moment of individual brilliance from Duke. 

Goodwin's cross from the right was deflected through to Duke, who adjusted his run magnificently before leaping with an arched back to flick the ball towards goal.

"Honestly [it's] the best moment of my life, up to date, in my football career," Duke said after the match.

"I'm just so happy and proud of the boys, we've made so many sacrifices to be here, it's the best feeling in the world."

Tunisia had been second best in the first half, but had two brilliant chances to equalise before the break.

Harry Souttar used all of his 198 centimetres to deny Mohamed Drager a goal with a magnificent sliding block.

Then, in stoppage time, skipper Youssef Msakni fired agonisingly wide from close range.

Australia had not led at half-time in 18 previous World Cup matches.

Tunisia was far better after the break, forcing Australia deeper and deeper as the game went on.