Whether it was complacency or stage fright, Australia's Sharks assure they'll be better for a reality-check loss that's stunted their giant-killing run to the Olympic quarter-finals.
Winless in four games before Monday, Japan came from 4-0 down to pip Australia 14-13, Charlie Negus's final-second attempt slipping off his fingers and high over the cross-bar at a rowdy La Defense Arena.
Still, defeat of the United States in a quarter-final on Wednesday would ensure Australia their best-ever men's Games result and pit them against the winner of Greece and Serbia for a spot in the final.
Australia began their campaign with a loss to Spain but then strung three remarkable wins together at the Paris Aquatic Centre against European heavyweights Serbia, France and Hungary to seal progression.
The loss to Japan, at the larger swimming venue, drew Australia level with Hungary at 3-2 and behind on goal difference.
But their victory over last year's world champions kept them in second place in their pool as they look to go deeper than an Olympics-best fifth achieved in 1984 and 1992.
"We got off to a good start and maybe we got complacent, they fought to the very end and they got the win," said left wing Luke Pavillard, who scored twice from four attempts.
"We would rather have this happen today than in two days.
"But this could be something that sets us up for the rest of the tournament in terms of our approach to each game and how we handle ourselves when we get in similar situations."
He said the size of La Defense Arena, usually a rugby stadium, had opened some teammates' eyes.
"Maybe that was a factor as well, like getting caught up in the scale of it," he said.
"All the boys were saying they hadn't played in front of a crowd that big.
"And it's going to be that big, or even bigger, in two days."
In-form Australian goalkeeper Nic Porter (six-of-12 saves) was rested at halftime, Japan scoring seven of eight goals either side of the main break to take a surprise lead.
They led by two goals at various stages in the final quarter before Australia levelled courtesy of a Milos Maksimovic backhand and Chaz Poot thunderbolt.
Replacement 'keeper John Hedges (three-of-11) then made a great left-handed save at 13-13 but Australia couldn't convert at the other end and Seiya Adachi snuck the winner under Hedges' armpit with 11 seconds to play.
Australia took a timeout and had a look at an equaliser but Negus flew his effort high and wide.
