As coach Ange Postecoglou prepares to punt on youth in unveiling his Socceroos' generation next, former captain Paul Wade has issued a dire World Cup warning.

"We are going to get absolutely smashed," Wade said.

Postecoglou will unveil a 30-man preliminary squad on Wednesday for next month's World Cup in Brazil to include several international novices and as many as a dozen A-Leaguers.

The likes of Adam Taggart, Osama Malik, Luke Brattan, Josh Brillante and James Troisi are favoured to be plucked from the domestic league.

"It's a massive step up for them, it really is," Wade said.

"But if you're organised, it's a great game, football, because you don't have to be the best team to win the game or to get a point.

"Unlike AFL, rugby league ... as long as you're clever, as long as you technically and tactically can do what the coach wants, bingo."

But Wade tempered any enthusiasm, noting the callow Socceroos meet top-shelf World Cup opponents Spain, the Netherlands and Chile.

"As a footballer, we talk about the green and gold. As a footballer, you have pride in yourself and your performance and helping your mates out. That all comes into play," Wade said.

"But right now, without doubt, we're going to get hammered."

Postecoglou will favour players likely to be available for the 2018 World Cup and Wade said he had nothing to lose.

"There's no pressure on him because we're not expected to get out of the group," he said.

"A lot of people are saying we won't even score a goal or get a point."

Postecoglou could name as few as five players unlikely to be around for the 2018 campaign - talisman Tim Cahill, striker Josh Kennedy, midfield spark Mark Bresciano, Matt McKay and possible third-string goalkeeper Eugene Galekovic - though Galekovic could miss and Newcastle Jets keeper Mark Birighitti be given glorified work experience instead.

Injury clouds also hover over several players including likely captain Mile Jedinak, who strained a groin in the English Premier League this week and is expected to miss the farewell game against South Africa in Sydney, and defender Curtis Good (hip).

Jedinak and Good will be named but the World Cup fate of Dutch-based defender Trent Sainsbury, who has been battling a knee injury sustained when falling on a sprinkler head last month, is uncertain.

Sainsbury had been pencilled in to fill a defensive posting vacated by the overlooked Lucas Neill and injured Rhys Williams.

Postecoglou will cut three players from the squad a day after Australia's friendly against South Africa on May 26. He will name his final squad on June 2. AAP