American young gun Jordan Spieth has upstaged Rory McIlroy and Adam Scott to score a runaway six-stroke Australian Open win.

The 21-year-old prodigy fired a spectacular course-record eight-under-par 63 in Sunday’s final round to finish with a 13-under total of 271 for the championship as his rivals struggled in more tough conditions at The Australian Golf Club in Sydney.

Veteran Rod Pampling (68) birdied the last two holes to clinch outright second spot at seven-under.

Brett Rumford (70), shot an even-par 71 to grab third at six-under.

Greg Chalmers (71) was fourth at five-under, with Scott (71) outright fifth, a further shot back.

Jake Higginbottom (69) was sixth at four-under, while McIlroy closed with a 72 to be tied 15th at two-over in his title defence.