OSLO -- Bert van Marwijk acknowledges that Australia are in urgent need of defensive reinforcement following their Oslo horror show against Norway.
Van Marwijk watched in disgust as his 37th-ranked side slumped to a 4-1 defeat at the Ullevaal Stadium and LA Galaxy striker Ola Kamara grabbed a hat trick for the hosts, who sit 20 places below the Socceroos in the FIFA standings.
The defeat on Friday was Australia's heaviest to a lower-ranked team since official rankings were introduced in 1993.
Kamara's treble and a header from Tore Reginiussen secured victory for the hosts after Jackson Irvine had given the Socceroos the lead with a 19th-minute header.
But the Hull City man's goal was the only positive on a freezing night when the Socceroos defence struggled badly.
It was a game to forget for Bailey Wright, playing in an unfamiliar right-back role, and Mark Milligan in particular, who struggled to get to grips with the pace of highly rated Basel winger Mohamed Elyounoussi and Kamara.
Van Marwijk pulled no punches and said the team desperately need the return of injured duo Trent Sainsbury and Sydney FC right-back Matt Jurman.
"I have a lot of information about this team and their defensive qualities," van Marwijk said. "We have two important players who trained this week for the first time but still couldn't play in Jurman and Sainsbury.
"But you can see we have problems when we defend. I hope that Sainsbury and Jurman stay fit and start to play in one or two weeks.
"We will work and search to nominate players who will make our defence better."
Van Marwijk handed debuts to Dimi Petratos and Andrew Nabbout, who worked manfully but struggled to make any real impression on the game.
But the Dutch coach said it was unfair to expect the inexperienced duo to shine when the team around them played so poorly.
Van Marwijk only met his full squad for the first time on Tuesday, with poor weather in northern Europe delaying flights.
However, the Dutchman believes there is enough time to improve the side before the World Cup opener against France on June 16.
"I have to find the right combination ... we need all the time to find it," he said.
"I will not complain about time because I knew the situation when I started.
"You never have enough time, but we have to do it ... and I am satisfied."
Australia face a 13th-ranked Colombia side in London on Tuesday, with Bayern Munich playmaker James Rodriguez sure to present a huge test for the under-fire defence.
However, Van Marwijk said it was too early to determine if he would make wholesale changes for the match at Fulham's Craven Cottage.
"How many changes? I don't know," he said.
"First I want to think about this game, talk with the players, analyse and then I start thinking about how we want to play against Colombia."