Australia will take a five-goal advantage to Quảng Ninh Province for Wednesday's second leg after defeating Vietnam 5-0 in Newcastle on Friday.
First-half goals from Sam Kerr, Chloe Logarzo and Emily van Egmond helped the Matildas establish a commanding three-goal lead.
It was a happy homecoming for Novocastrian van Egmond, who returned to her home town to score the third goal before Clare Polkinghorne scored a fourth and Kerr a fifth from the penalty spot to secure a confident home leg victory.
In what was the team's first match in Newcastle since November 13, 2018, Ante Milicic's side proved too strong for the nation ranked no. 32 in the world and are now 90 minutes away from booking a ticket to the 2020 Tokyo Olympic Games.
The squad flew out to Vietnam on Saturday to prepare for the second leg at Cẩm Phả Stadium in the Quảng Ninh Province, knowing that a similar performance on Wednesday, 11 March 2020 will secure the Matildas’ fourth-ever appearance in the Olympic Games women's football tournament, but Polkinghorne – a veteran of four previous Olympic Qualifying campaigns – says she is certainly is not looking beyond the second play-off leg just yet.
“We’ll get there first, then we’ll take the next few months as they come,” Polkinghorne told reporters prior to departing for Vietnam.
She added: “It’s always nice to get a victory and a clean sheet. I think half the job is done, we’ve got to ensure we recover and prepare well for the next game.
“The way that Vietnam play sometimes it can be hard to break down, but I thought we were really patient and found some good solutions, and had a little bit of variety in there as well.
“That’s something we’ve been working on and hopefully we can continue to improve on that.”
The Matildas last played in Vietnam at the 2014 AFC Women's Asian Cup, where the team defeated Vietnam 2-0 on their way to the tournament final.
Midfielder Elise Kellond-Knight explained the team will draw on their prior experiences of playing in south-east Asia and are confident they will get the job done.
“It’s always a challenge playing in Asia, we haven’t been over there for a number of years now,” she explained.
“The conditions are extremely different, the grass, the surface is always a lot different, it’s like buffalo thick grass.
“It will be interesting to get over there and get situated, we’ve only got a couple of days to prepare.”
Should Australia qualify, they will join host nation Japan and the winner of the other AFC play-off between Korea Republic and China PR at the Games in July and August.
Vietnam v Australia (Away Leg)
Date: Wednesday, 11 March 2020
Kick-off: 6 pm local, 10 pm AEDT
Venue: Cẩm Phả Stadium, Cẩm Phả, Quảng Ninh Province, Vietnam