Australia captain Aaron Finch claimed his side could have passed 350 in a win against Sri Lanka that moved them top of the Cricket World Cup's group-stage table.

Opener Finch blasted 153, the joint-highest score of the World Cup so far, as well as equalling his own ODI record tally, as Australia racked up 334-7 at The Oval on Saturday.

And with Mitchell Starc in fine form, taking 4-55 including removing dangerous opener Kusal Perera for 52, Australia had their fourth win from five games as Sri Lanka fell short by 87 runs.

A semi-final spot is now in sight for Australia, with Finch's side next in action against Bangladesh at Trent Bridge on Thursday.

"It was nice to get a couple away early, it's key to my batting and if I'm getting drives away it's a good sign," said Finch after collecting his award for player of the match.

"It's a nice wicket, I've been working on getting my balance spot on from ball one. I've been out first ball a few times so it's key for me to do that.

"We lost some wickets when I was trying to take the game on, maybe a bit too much at times, but the first partnerships were key to getting our score.

"They bowled excellently, we could have got over 350, but they put the pressure on superbly at the end."

Steve Smith made 73 as the duo put on 173 for the third wicket to take the game away from Sri Lanka.

"He gets off strike so easily and scores boundaries so easily," Finch said of Smith. "He just hits the ball in the gap and it's a great skill early in the innings."

In response Sri Lanka were 115 without loss and seemingly on track to chase down a massive score but they were pegged back by Starc as well as Pat Cummins, who took 2-38, and Kane Richardson, whose 3-47 included the scalp of captain Dimuth Karunaratne.

"Finch and Smith batted well, but we came back strongly," said the Sri Lanka skipper, who made 97.

"We started well, but the middle order couldn't capitalise. They had to handle pressure and keep the momentum going.

"Starc and Cummins are world class, we knew what they could do, we had to keep a plan but we didn't.

"We lost couple of games to the rain, now we need to win a couple of games."

Sri Lanka's next game is against hosts England in Leeds on Friday.