An experimental Australia line-up suffered a disappointing 1-0 loss to Venezuela on Saturday, where they were noticeably flat and lacked punch, while having just 34 per cent of possession.
While the Socceroos have been defensively sound and disciplined under Tony Popovic, they have often struggled for creativity in possession.
McGree stressed Australia had fielded four debutants against Venezuela, while other players were out of position, and expected chemistry to grow with time.
"We're comfortable being out of possession at times," he said.
"We're confident that we can keep the ball out of the back of our net and defend as a unit, as a block, and if we get our press right and retain the ball and win the ball back and then to have the confidence to keep the ball.
"... Especially leading into the World Cup and the game against Colombia, we're going to have to show that we can keep the ball and play possession.
"And I think that comes with time and with playing together and experience."
The Socceroos are yet to review their loss to Venezuela but McGree identified what needed to be better against world No.13 Colombia at Citi Field in New York on Wednesday.
"It's the kind of non-negotiables: the work rate, the first and second balls, and the desire to press, to tackle, to run," he said.
"I think the things that we can control need to be controlled well, and we need to do them well in order to compete and to give ourselves the best opportunity to win.
"And then I think we've got quality enough to create chances and take chances and keep the ball out of the back of the net."
Against Venezuela, Middlesbrough attacker McGree, 27, made his international return after a lengthy stint on the sidelines with a foot injury.
"It's been toughest mentally over anything," he said.
"I think the physical aspect of it is you show up every day, you do always prescribe the view and what the physios tell you to do, and you go out there and do your best.
"But I think mentally, the setbacks are the thing that really took a bit of a toll.
"And in the end, we were able to, through club and country ... find what worked and how we could combat the issues. And I'm fortunate to be here and back and fit, and hopefully I can stay that way."
While McGree was sidelined, Mohamed Toure, Nestory Irankunda and Connor Metcalfe have proved a dynamic front three.
"We've got some really exciting talents and explosiveness, some real quality and technical ability," he said.
"Having that competition for places in attack is only going to promote better performances and more hunger and desire from everyone involved."
Defender Jason Geria has departed camp after suffering a left hamstring injury against Venezuela.
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