When Awer Mabil's childhood dream of playing in the UEFA Champions League becomes reality this week, it will come after living through a nightmare in 2019.

The winger had the world at his feet after a breakthrough Asian Cup for the Socceroos in the United Arab Emirates at the start of last year.

Mabil scored two goals in his first senior tournament for Australia, capturing headlines back home for a unique, eye-catching goal celebration paying tribute to people coping with mental health problems.

Within hours of Australia's quarter-final exit to the host nation, however, Mabil's world came crashing down.

A car accident in Adelaide claimed the life of Mabil's 19-year-old sister Bor, leaving him devastated with grief.

"I was enjoying the time of my life, playing for my country, scoring for my country at a tournament," Mabil said.

"All of a sudden, that happened - my best friend who I was talking to every day, suddenly gone like that.

"I lost my passion for a lot of things, for at least six months. I kept working hard but at the same time I didn't have the joy."

With the support of the Socceroos and coach Graham Arnold, as well as his Danish club FC Midtjylland, Mabil worked his way through the devastating loss.

Slowly, as the pain and anger subsided, a love for football - and life - was rediscovered.

Drawing on his own history of using his story and profile to help others, Mabil hopes his path back to happiness can be another opportunity to set an example.

"The last seven months I found my happiness again, in life and in football," he said.

"I know now I only have one job and that's to try to set a way, a path for the next to follow.

"That's my job, just to show people that no matter what you go through you can still overcome things.

"That's what I feel, that's my purpose now."

That return to joy has coincided with another big step in Mabil's career.

The 25-year-old played a key role in helping Midtjylland reach the group stages of this year's UEFA Champions League - the first time in their history they'll be on the biggest stage in European club football.

Mabil's team has been drawn alongside English Premier League champions Liverpool, Dutch heavyweights Ajax and Italy's shock quarter-finalists from last season Atalanta.

The kid who used to wag school as a youngster in Adelaide to watch Champions League matches will now be Australia's only representative in the elite competition - playing at three of the most historic venues in European football in Anfield, the San Siro and Amsterdam's Johan Cruijff ArenA.

It's a long way from Mabil's first exposure to European football during the early years of his life at a refugee camp in Kenya.

The son of South Sudanese refugees walked two hours from the camp to the nearest TV to pay $1 and watch football matches where he didn't really understand who was playing, or in what competition.

"I thought it was just watching football, because I couldn't understand English at that time," he said.

"I was just going there to support my favourite team.

"It wasn't until I came to Australia that I realised what the Champions League was - the best for club football you can go to.

"I grew up watching Liverpool and seeing Anfield, the anthem they sing ... to be able to play at that ground is going to be amazing.

"To play at San Siro... that will be amazing.

"And Ajax - I was on trial with Ajax before I came to Midtjylland, but it never really worked out.

"It's time to go back and show them a little something, I hope."

Mabil is also excited for Midtjylland, the club which he says has helped him become a man since joining them in 2015.

Founded in 1999, the Ulvene (Wolves) have already won three Danish Superliga titles in their short history, focusing on developing young talent such as Mabil.

While the Champions League debutants start as the minnows in their group, Mabil says he and his teammates have no fear ahead of their campaign starting at home against Atalanta on Wednesday (Thursday 0600 AEDT).

"It's not easy, but I think there's a possibility where we can surprise some people," Mabil said.

"We have nothing to lose. No-one is expecting us to do anything.

"But we know how dangerous we are. If anyone switches off we're going to punish them - that's our mentality going into the group."