New Matildas coach Tony Gustavsson will think outside the box as he attempts to fill two massive defensive holes in upcoming games against soccer powerhouses Germany and the Netherlands in Europe.

Gustavsson already knew he would be without star left back Steph Catley as she continues her rehab from injury, but the squad was dealt a huge blow on Wednesday night when fellow wing back Ellie Carpenter was ruled out after a COVID-19 breakout at her French club Lyon

The duo are considered among the best in the world at their positions, and Gustavsson now faces big decisions on how to replace them.

The Swede was keeping his cards close to his chest ahead of Sunday's (AEST) game against Germany, saying he could turn to a left back to replace Carpenter at right back, use more attacking players to in the wing back positions, or push a centre back out wider.

"We've been spending days in training to see how we're going to fill that position," Gustavsson said.

"And without revealing too much, we might see some different options through these two games, because we need to take this opportunity to look at other solutions.

"Depending on what's going to happen come Olympics, we'll need to find different ways of solving positions. Right now we're lacking options, so don't be surprised if you might see multiple solutions during these two games."

Midfielder Amy Harrison was also ruled out from joining the Matildas squad on Wednesday night due to COVID-19 protocols.

Katrina Gorry (pregnancy), Elise Kellond-Knight (injury), and forward Kyah Simon (injury) are others who are missing from the squad.

World No.2 Germany are the defending Olympic champions, while the world No.4 Netherlands made the 2019 World Cup final.

The seventh-ranked Matildas haven't played in more than a year, and will start as underdogs in both games.

But Gustavsson, who will be coaching the Matildas for the first time, isn't one to put up the white flag.

"Someone said to me,' Tony, you know that this might be one of the toughest games that the Matildas have ever played'," Gustavsson said.

"I said, 'What do you mean?' And they said, 'Well look at the players not available, the team haven't played in 400 days, they have a new coach, it's hailing when you're practising'.

"I could stand here and give you excuses and say results wise we don't expect to do well. But we're not wired that way, we're the Matildas."