QATAR - Australia defender Bailey Wright was grieving on Thursday, having learned after the Socceroos' 1-0 upset of Denmark at the World Cup that his mother-in-law had died.

Wright, who plays for Sunderland in the second tier of English soccer, had told Australian reporters he had grave fears for his mother-in-law's health after receiving a message from his wife after the match on Wednesday.

Football Australia confirmed on Thursday morning that Wright's mother-in-law had died and the defender would not appear for media.

Wright had paid an emotional tribute to his mother-in-law and wife at the stadium on Wednesday night.

“I’ve just come in from a message from my wife. I just want to dedicate this to my wife, bless her, and her mum," Wright had said at the stadium late on Wednesday.

"I’ll be honest, I’m not sure if she’s still with us.

“It was, for them, a really tough time back home, but ultimately it made this possible for me to be here and live one of my dreams so I dedicate that to Tammy."

Wright said he had not told his team mates about his worries back home.

"No one knows. That’s something I’ve kept to myself; we’ve all got a lot going on. Job to do, isn’t it? You’ve got to be professional all the time," he added.

Graham Arnold's Australia meet Argentina in the last 16 at Qatar, only the second time the Socceroos have made the knockout phase. Australia were knocked out of the last 16 at the 2006 World Cup by eventual champions Italy.

Few gave Australia much of a chance to advance from a group that also featured 2018 champions France and Tunisia.

However, the Socceroos had already shown through an arduous qualifying journey that they liked doing things "the hard way", said Wright.

"When we set out on this journey four years ago, Arnie (Arnold) said to us what he wanted us to be about — our mateship and togetherness is what’s going to make us create history,” he said.

"It’s 11 brothers out there, whoever comes on, and it’s pretty special to be part of that.

"When you’re part of something like that, it’s difficult to really actually put it into words, what it feels like. It’s a real feeling.

"A few of us have said now that that feeling kind of won the game today."

(Reporting by Ian Ransom in Melbourne; Editing by Peter Rutherford and David Goodman )