Aaron Finch hit the highest score by an Australian at the Cricket World Cup to guide his side to a comfortable 87-run victory over Sri Lanka in England.
Finch propelled the defending champions into a winning position as he led the recovery from a slow start to score 153 runs off 132 balls at The Oval in London.
His total helped Australia post a challenging target of 335 to win for Sri Lanka, who got off to a flier in pursuit of a record World Cup run chase.
Captain Dimuth Karunaratne and Kusal Perera put on 115 for the first wicket before the latter was out for 52.
Sri Lanka managed to steady the ship but Karunaratne's departure when on 97 was the catalyst for a collapse which ended their chances of victory.
The Asian side lost their last six wickets for 42 runs as they collapsed from 205-4 to 247 all out.
Mitchell Starc was the pick of the Australian bowlers, finishing with figures of 4-55 as the 2015 winners moved to the top of the 10-team table.
Australia made a laboured start to their innings before Finch took up the mantle and began despatching the ball to all corners of the ground.
His 153 surpassed the unbeaten 140 amassed by Ricky Ponting at the 2003 World Cup in South Africa, Zimbabwe and Kenya.
After Finch had been removed by Karunaratne, Steve Smith scored 73 and Glenn Maxwell hit an unbeaten 46 as Australia ended on 334-7.
Karunaratne and Perera threatened to make light of the chase as they made a superb start before Starc and Kane Richardson ripped through the middle order to seal their fourth win of the tournament.
In the other match played today, South Africa picked up their first victory as they thrashed Afghanistan by nine wickets at Cardiff Wales Stadium.
Afghanistan collapsed from 69-2 to 125 all out in an innings disrupted by rain.
In reply, a cautious South African batting line-up gradually knocked off the required runs and won with 19.3 overs to spare.