Glenn Maxwell's lightning-quick century has propelled Australia to 6 for 376 to set Sri Lanka a formidable target in the World Cup match at the SCG.

Maxwell fell just short of hitting the quickest-ever World Cup century, but made the milestone - his first in one-day internationals for Australia - in 51 balls, smashing a woeful Sri Lankan attack for 10 boundaries and four sixes.

While openers Aaron Finch (24) and David Warner (9) fell cheaply, Michael Clarke showcased his value to the batting line-up with a run-a-ball 68, alongside Steve Smith (72) in a 134-run partnership for the third wicket.

But their dismissals brought Maxwell to the crease, who along with a rejuvenated Shane Watson (67 off 41), proceeded to pummel Sri Lanka into submission.

Australia 376 for 9 in 50 overs (Steven Smith 72, Michael Clarke 68, Glenn Maxwell 102, Shane Watson 67; Lasith Malinga 2 for 59)