New Zealand will face rivals Australia in the Rugby World Cup final after an Adam Ashley-Cooper hat-trick helped the Wallabies to a 29-15 victory over Argentina at Twickenham on Sunday.

Daniel Hourcade's side delivered one of the performances of the tournament to see off Ireland in the last eight, but started slowly on this occasion and were then hampered by injuries to in-form wing Juan Imhoff, skipper Agustin Creevy and influential centre Juan Martin Hernandez.

Having been 14-3 down inside 11 minutes, the Pumas - cheered on by football great Diego Maradona - nevertheless fought valiantly to stay in the game, setting up a tense last quarter.

Yet Australia, for whom David Pocock delivered another fantastic display at number eight, were not to be denied a fourth final appearance and Ashley-Cooper's third try - with eight minutes remaining - ensured they will have the chance to spring an upset against defending champions New Zealand next weekend.

Having racked up 17 unanswered points in the early stages of their quarter-final, Argentina were on the receiving end of a blistering start this time around as Australia scored the fastest try of the tournament to date.

An inside pass from Nicolas Sanchez was telegraphed by Rob Simmons and the lock had the simple task of running in by the posts with 68 seconds on the clock.

Nicolas Sanchez got Argentina on the board with a penalty, but a superb cut-out pass from Bernard Foley enabled Ashley-Cooper to race over for his first score - Australia's fly-half landing his second conversion from the touchline.

Although Sanchez contributed a second three-pointer when Australia collapsed a scrum, Argentina suffered a trio of setbacks as Imhoff and Creevy were forced off either side of Tomas Lavanini being controversially sin-binned by referee Wayne Barnes for tackling without his arms.

Australia capitalised on their numerical advantage when Ashley-Cooper accepted another cut-out pass, this time from Matt Giteau, to cross on the left following excellent work in the build-up from Israel Folau.

Yet the Pumas refused to give in and Sanchez made it 19-9 with a third penalty before a wonderful break from Santiago Cordero almost provided a first Argentina try on the stroke of half-time.

Despite losing another player to injury in Hernandez, Argentina got back within a converted score five minutes into the second period - after a sloppy missed kick from Foley - thanks to another penalty earned at a scrum.

Foley restored Australia's 10-point cushion with his next attempt from the tee, but Sanchez responded in kind in the 55th minute as Argentina continued to pose problems with their energy and physicality.

Tension levels rose around Twickenham with Argentina appearing increasingly capable of pulling level, but a stunning cross-field run from Drew Mitchell set up Ashley-Cooper's third try - amid suspicions of a forward pass - and dashed the hopes of the Pumas.