Australia teed up a blockbuster clash with either South Korea or Saudi Arabia with their heaviest win in Doha on Sunday.
The Socceroos received some additional good news on Monday, with right-back Gethin Jones cleared of a serious groin injury after being forced from the field in the 69th minute.
Australia took the lead via Elkan Baggott's own goal in the 12th minute, then doubled it through Martin Boyle's 45th-minute diving header.
Craig Goodwin came off the bench to score a 89th-minute volley and assisted Harry Souttar two minutes later to complete the victory in front of 7863 fans at Jassim bin Hamad Stadium in Doha.
� HIGHLIGHTS | 🇦🇺 Australia 4�⃣-0�⃣ Indonesia 🇮🇩— #AsianCup2023 (@afcasiancup) The Socceroos cruise into the Last 8 at the expense of Garuda! Match Report 🔗 https://t.co/fj8ywDCMDA#AsianCup2023 | #HayyaAsia | #AUSvIDN pic.twitter.com/PcycVAjrWGJanuary 28, 2024
"It was a tough game but obviously the quality that we've got up front came through," Arnold said.
"The improvements today was the individual belief and some of the actions the boys were doing. It was, in a lot of ways, more freedom from them and more relaxed.
"And that's what I want. I want them to show their individual qualities.
"It's good to have a great system of play, and it's good to have great attacking patterns.
"But I'd rather see these boys relax and show their skills and show their imagination - and I saw that growing today."
Jones went to hospital for scans but was a relieved man on Monday.
Socceroos defender Gethin Jones is fouled during the clash with Indonesia. (AP PHOTO)
"All clear," Jones said.
"This is new to me - like different kind of competition to what I'm used to at club level and it's taken a lot out of my legs.
"I felt my left groin, a bit of fatigue after the Syria game, obviously I felt the same yesterday. But the results came back all clear, so I just know it was fatigue.
"I can recover now and be ready for the next game."
South Korea and Saudi Arabia play on Tuesday (Wednesday 3am AEDT), with the quarter-final scheduled for Friday (Saturday 2.30am AEDT).
"We get a couple of days off now to rest and recover which is crucial," Arnold said, after conceding his charges could improve "in every aspect".
Australia didn't have a shot until Boyle's goal and didn't record a second until the 80th minute. With a pro-Indonesia crowd bringing a loud, parochial atmosphere, the Socceroos' defence looked panicked.
Indonesia goalkeeper Ernando Ari is beaten by Martin Boyle's header that put Australia two up. (AP PHOTO)
Australia drew first blood when Irvine burst down the right and into the box, before his attempted cross took a heavy deflection off Baggott and beat goalkeeper Ernando Ari.
For the second, Jones launched a wonderful cross-field ball towards the far post, where Boyle flung himself forward to head home.
Indonesia faded in the second half as Mitch Duke (hamstring) and Goodwin (knee) returned from injury in the 61st and 86th minutes respectively.
In the dying stages, Australia broke through again when Connor Metcalfe cleverly backheeled to Atkinson, and the full-back picked out Irvine.
The midfielder's header was well saved by Ari, but Goodwin pounced on the rebound and buried a skidding volley.
Two minutes later, from a free kick, Goodwin turned provider for Souttar, who turned home a lovely header.
"I know there's people back in Australia asking for or wanting to see what an impact player is off the bench," Arnold said.
"Maybe that's a good role for Craig Goodwin."
