The Matildas took a 5-0 lead into the return leg of a home-and-away Olympic qualifier and led Wednesday night's match 2-0 by half-time after captain Sam Kerr and forward Hayley Raso both scored.

The match, which was played in front of an empty stadium, was delayed for around 15 minutes after the ground's lights went out in the first minute.

Vietnam scored on the counter in the second half - a moment which energised the hosts - and Australia again missed several chances on goal throughout the match, including a Chloe Logarzo penalty in the first half.

Australia progress 7-1 on aggregate but will have plenty to work on ahead of Tokyo.

Matildas coach Ante Milicic praised his side's performances and conduct throughout the past six weeks of an extended qualification campaign.

"I'm delighted for the girls. They have deserved it," Milicic said post-match. "They worked ever so hard for the majority of the game tonight.

"It's been a long journey with a lot of different scenarios thrown up, a lot of changes in timetables. Even tonight was never going to be easy coming here, on this pitch, without the crowd, the lights going off, with the 5-0 advantage from the first game.

"Over the two legs, we were the much better side, so congratulations to the girls and the staff and they are looking forward to going to a major tournament."

Tokyo 2020 will mark the first time in 16 years that Australia will have representatives in both the men's and women's Olympic football tournaments.

Matildas goalkeeper Lydia Williams conceded it was a "pretty scrappy game" but the main thing was "we did the job, we got the three points and we're going to Tokyo".

"We really believe in our team, in each other and in what we can do and I think just qualifying is hard enough in itself and I think the fact that we have done it with two really hard tournaments in different places, I think it's a good step in the direction we want to go," Williams said.

The Matildas squad will be finalised over the coming months but van Egmond has been a stand-out throughout qualification and looks bound for her second Olympics appearance, if it goes ahead.

There is talk the Olympics will be cancelled due to coronavirus.

Australia bowed out in the quarter-finals at the hands of Brazil in Rio four years ago. It was the Matildas first appearance at an Olympics in 12 years.