France started their World Cup title defence in style with a 4-1 comeback win against Australia on Tuesday, with Olivier Giroud scoring two goals to become Les Bleus' joint all-time top scorer.

Giroud netted before and after the break to take his tally to 51 goals, matching Thierry Henry's mark. He scored either side of a Kylian Mbappe goal after Adrien Rabiot had levelled for France following Craig Goodwin's shock early opener.

Les Bleus are the first defending champions to win their opening match since Brazil in 2006, which has already put them in a good position to advance from the group phase, something Italy in 2010, Spain in 2014 and Germany in 2018 failed to do.

France, whose defender Lucas Hernandez was ruled out of the World Cup after picking up a serious knee injury in the first half, have three points and lead Tunisia and Denmark by two after they played out a 0-0 draw on Tuesday.

Didier Deschamps's side, who started the tournament on the back of the disappointment of striker Karim Benzema being ruled out injured last Saturday, next face Denmark on Saturday.

"We got a scare but reacted quickly afterwards. Even if we could have scored more goals, we found each other, we were efficient," said 36-year-old Giroud, who is now France's oldest scorer in the World Cup.

"It's very good for our self-confidence to have turned things around. We'll have to learn from these little mistakes however."

Australia coach Graham Arnold said his team ran out of gas against a superior side.

"Look, at the end of the day, they're are a quality side. They are world champions for a reason," he added.

"I thought the first half, we did well. Second half, we ran out of legs a bit, but that’s the type of level of those players play at."

Poor start

It was not quite the start France were expecting at the Al Janoub stadium.

Australia's Goodwin smacked the ball into the roof of the net from Mathew Leckie's cross from the right, leaving Lucas Hernandez holding his right knee after being beaten to the ball after nine minutes.

Hernandez's brother Theo came on as a substitute and France continued to struggle to create space, with only Mbappe threatening on his left flank.

Australia were much more direct, making the most of Les Bleus's non-existent midfield.

It was Rabiot who levelled in the 27th, however, leaving his marker behind to head home from Hernandez's cross.

With Mbappe moving more centrally, the Australia defence had another problem to deal with and that was clear when the Paris St Germain forward's backheel inside the area was collected by Rabiot, who slid the ball across for Giroud to tap in.

France played more freely from then on, with Antoine Griezmann's low shot going just wide and Mbappe skying his attempt over the bar as he raced to meet Griezmann's cross from the right.

Australia kept France on their toes and came close shortly before halftime when Jackson Irvine's header grazed Hugo Lloris's right-hand post after a rebound.

Mbappe caused more chaos early in the second half but could not quite find the breakthrough, until he silenced the Australia fans, who in the first half were shouting 'Who are you?' at him, with a glancing header in the 68th minute.

Three minutes later, Giroud headed home from Mbappe's cross before falling on his back in apparent disbelief and being surrounded by his team mates in a goal celebration that lasted longer than usual, giving an exhilarating feel to France's win.

It took Giroud, who owed his place in the starting lineup to Benzema's absence, 115 international appearances to score his 51 goals, while Henry needed 123 from 1997-2010.

There were more chances for France through Theo Hernandez and Ibrahima Konate but the result was already satisfying enough, bearing in mind that in 2002 their title defence started with a 1-0 loss to Senegal followed by a first-round exit.