Australia have taken an 18-3 advantage into half time of their opening Rugby World Cup fixture against Fiji thanks to David Pocock's quick-fire double.

The Wallabies were on top in the early stages, without truly being able to cause their opponents any real problems in a cagey start to the contest.

Fiji were dealt an early blow when Waisea Nayacalevu was stretchered off the field with what appeared to be a tournament-ending injury.

A slack forward pass from the Pacific Islanders then gifted Bernard Foley the chance to get his - and indeed Australia's - first points of the competition when finding the sticks from close range.

John McKee's men, currently ranked ninth in the world, soon hit back when Nemani Nadolo followed suit by himself kicking over after the much-fancied Aussies conceded two penalties in quick succession.

Buoyed by that, a period of Fiji domination followed when a wave of attacks ended narrowly short, and that would ultimately prove costly as the Wallabies soon found their stride.

Skipper Stephen Moore successfully picked out Pocock from a dangerous lineout, allowing the openside flanker to cross over for his fifth Test try in the famous yellow and green strip.

Foley made no mistake from the conversion to keep alive his perfect early kicking record, while there was more joy to come five minutes later when Pocock found the whitewash for a second time.

The score - which makes Pocock his country's record-scoring forward at a World Cup - came directly on the back of Campese Ma'afu being shown a yellow, as Fiji began to crumble in the latter stages of the opening 40 minutes.

There was still time for Foley to extend the two-time winners' lead even further when more handling errors from the Fijians saw them punished in the closing moments of a half that had shown so much promise at one stage.

Follow Sports Mole's coverage of the second half right here.