It was eerie not to hear any noise from the Japan dugout but that dramatically changed from coach Kenji Hasebe's troops in the final quarter.
The big movers would have had to have been Australia (two points), Vantage Black Sticks and Team USA (one each).
Coach Paul Gaudoin's women, playing in alternative gold and navy blue strips, did just that.
Jordyn Holzberger made good with a field goal in the eighth minute for a 1-nil lead only a minute after Gabi Nance had deftly brought down a waist-high pass, apologised for the delay, dribbled it deep into the D but couldn't deposit it into the net past sprawled Japan goalkeeper Megumi Kageyama.
But the world No 4 Aussies weren't done. Two minutes later it was rookie striker Madeleine Ratcliffe's turn to rattle the backboard, 2-0, from another field goal, although a hyped-up Nance picked up a green card for a foul.
Undefeated Japan, looking somewhat relaxed on a chilly 17C day, showed some intent on attack in the second quarter but a porous Aussie defence for the first two rounds confirmed they have a backbone but were just taking their time to show it.
After a scoreless third quarter when the women in pink took charge a little more, it wasn't until the first minute of the final 15-minute spell that appropriately captain Hazuki Yuda got them in a huddle to exchange high fives amid squeals of approval from a penalty corner, 2-1.
Two minutes later, they rode on that adrenalin fix to yield back-to-back penalty corners but, instead of scoring, defender Emi Nishikori collected a green card for two minutes of downtime in the naughty chair.
But the Aussies stopped the rot for the rest of the quarter to secure maximum points.
Hockeyroos captain Jane-Anne Claxton said her team, who mostly have fewer than 10 caps, were delighted to chuck the monkey off their backs.
"It was a decent win against Japan who are quite highly rated off the [Rio] Olympics and performing at this tournament," said Claxton, who felt the Aussies had a lion's share of attacking play.
However, the 26-year-old midfielder from Perth rued the lack of discipline late in the second half which yielded a rash of free hits and penalty corners.
"We have to tidy up a full 60 minutes of hockey rather than 30 minutes and lagging off but that is an experience thing."
Claxton saluted her backline, especially the newbies, for a staunch display when they looked a little vulnerable with some tight marking.
"In terms of points and scoreboard pressure we needed to stay in the top two going into the next round so it's good to have a win and, hopefully, a few more."
Claxton said Australia counted their blessings when it didn't rain today in their game.
"I'm just glad the pitch didn't flood and, hopefully, we'll get some warmer weather in the week."
A smiling Yuda said the Aussies' first-half two goals was like a kick in the guts for world No 10 Japan.
"The defence conceded the goals but for us it's like the whole team let us down a bit so we all have to work as one in the next game," she said after a poker-faced meeting in front of their dugout at the final whistle before playing the Black Sticks tomorrow at 6pm.
Yuda said the cold weather wasn't really a factor.
