Steven Smith (72) and Michael Clarke (68) shared a 134-run third-wicket partnership to set the innings up before Maxwell posted his maiden one-day international hundred and Watson chimed in with a career-reviving 67 in a 13.4-over stand that helped lift the four-time champions to 376 for nine the highest total ever against Sri Lanka at the World Cup.

Australia bowled out Sri Lanka for 312 in 46.2 overs for a 64-run win to move into second spot in the group behind New Zealand with a game remaining against second-tier Scotland likely avoiding a detour to New Zealand during the knockout stage.

The Sri Lankans chased bravely after losing Lahiru Thirimanne (1) with Sangakkara (104) notching his third consecutive hundred and surpassing 14000 career runs in ODIs and sharing a 130-run partnership with Tillakaratne Dilshan (62) that had Australia under serious pressure in the early overs.

Maxwell's 'innings was the standout for me but Sangakarra again and the whole Sri Lankan batting order put us under pressure that's for sure' said Clarke who won the toss and chose to bat in ideal conditions. After Australia slipped to 41-2 Clarke and Smith lifted the total to 175 before both fell within five balls.

Clarke scored a run-a-ball 68 in his first decent innings since hamstring surgery in December before he was bowled by a perfect yorker from Lasith Malinga (2-59) in the 32nd over. Smith was caught off Dilshan in the next over.

That's when the fireworks started with Maxwell belting 102 from 53 balls narrowly missing a World Cup record for the fastest hundred as he batted with Watson. Maxwell's hundred came off 51 balls one shy of the record but he did have some luck on 93 when wicketkeeper Sangakkara chased a thick edge off Angelo Mathews' bowling but couldn't glove the catch.

After running two to reach triple figures he gave Watson a long hug beside the pitch. 'It's a big relief ... a massive weight off' said Maxwell who scored 11 half-centuries in his previous 44 ODIs. 'Hopefully it's the first of many.

'And obviously having Watto there he's been there for me over the last couple of tough weeks off the field but he's been there with me through thick and thin and I shared a little special moment with him out there hopefully it's going to open the floodgates a little bit and I can stop getting out in the 90s.'

His innings contained 10 boundaries and four sixes before he hit a full-toss from Perera (2-87) to Malinga at mid-on to spark a late flurry of wickets including three in the last seven balls.

Watson who was dropped from the starting lineup to a lack of consistent runs before Australia's World Cup-record win over Afghanistan last Wednesday got a surprise recall in Sydney at Mitch Marsh's expenses when selectors decided his extra experience was needed in the bowling.

The Sri Lankans were on target for the first half of the innings with Sangakkara and Dilshan in aggressive form. The pair belted 31 runs in eight balls in one sequence with Dilshan smacking Mitchell Johnson (2-62) for six consecutive boundaries in the sixth over. Both eventually fell to allrounder James Faulkner (3-48) with Dilshan trapped lbw to end the partnership and Sangakkara caught in the deep after facing 107 balls.

He was hit on the inside of the right heel by a full yorker from Mitchell Starc (2-28) on 99 and hobbled for the rest of his innings. Dinesh Chandimal retired hurt on 52 in the 41st over with an injured leg curtailing Sri Lanka's prospects.

'It was a bit too much to chase' Sri Lanka skipper Mathews said. 'We conceded 200 runs in the last 16 overs and it was too much.' Sri Lanka runners-up in 2007 and 2011 hasn't beaten Australia at the World Cup since winning the 1996 final.