Glenn Maxwell said he felt he'd got a "monkey off the back" after his maiden one-day international hundred powered Australia to a win over Sri Lanka in their World Cup in Sydney on Sunday.

Maxwell's blistering century, his first in 43 ODI innings, came off just 51 balls -- the second-fastest in World Cup history behind Kevin O'Brien's 50-ball assault for Ireland against England in Bangalore four years ago.

"It was nice to get the monkey off the back," said Maxwell. "I have scored a few 90s so to finally hit the hundred was a relief.

"The top order set it up beautifully for me and Shane [Watson] to go berserk at the end.

"I didn't know about the record World Cup century but I knew about the Australian record [57 balls] because James Faulkner doesn't shut up about it," said Maxwell.

"Credit to the boys for the way they battled -- Maxwell scoring his first ODI hundred, we needed his runs today," said Australia captain Michael Clarke.

"If we can hold our nerve like that we give ourselves a chance. Watching players around the world scoring so quickly and freely, teams can chase any score now."

Sri Lanka captain Angelo Mathews had no doubt about where the match was won and lost.

"We conceded 200 runs in the last 16 overs and it was way too much," he said. "We've got to improve in our bowling and fielding. If we can keep the opposition to 300, we can chase it down."

As for the 37-year-old Sangakkara's latest century, Mathews added: "He's brilliant. He's ageing and he's getting better and better."