Australia coach Tony Gustavsson insisted Wednesday it was simply bad luck that two players were concussed in separate "high-intensity" training incidents on the eve of their Women's World Cup clash with Nigeria, and praised his team for how they responded.

The Matildas were already without the injured Sam Kerr for the match in Brisbane on Thursday and now fellow forward Mary Fowler – who replaced the Chelsea star in their opening game – is also unavailable.

With Kyah Simon still recovering from a knee injury sustained in October, Arsenal's Caitlin Foord is their only recognised striker.

Along with Fowler, defender Aivi Luik, who was a substitute in their 1-0 win against Ireland last week, also suffered a head knock in training and has been ruled out.

"It was a completely normal training, two days out you always have high-intensity," said Gustavsson, who refused to say how the incidents unfolded.

"Everything was good, we were just unlucky unfortunately, two head knocks. We didn't do anything different than normal.

"The players kept going ... they are on a mission, and just focused on what they can control so credit to them in yesterday's training on how they responded to it."

Gustavsson had no update on Kerr's calf injury, saying only that she would be re-assessed after the Nigeria game.

"We want to wait until the last minute to see where's she's at in terms of availability," he added, referring to their final Group B match, against Canada on July 31 in Melbourne.

His options against Nigeria appear to now be starting Foord up front with Emily van Egmond or Tameka Yallop, who both usually play in midfield.

Australia have three points and victory would ensure they progress to the last 16 from Group B. Nigeria and Canada have one point each, with Ireland yet to get off the mark.

QUALITY

Nigeria coach Randy Waldrum warned a depleted Australia still have plenty of "weapons" and it would not change how they approached the game or give them an advantage.

"I don't think it really changes our tactics and what we are trying to do. They obviously still have a lot of weapons that can hurt you," said the American.

"We know the strength of their team, I know a lot of their players well from when I was coaching in the (American) NWSL, I know their quality.

"So we cannot go into the match thinking we are at some advantage for that reason. We have to stick to the game plan and how we have been preparing for them since after the Canada match."

Nigeria opened their campaign by earning a valuable point in a battling 0-0 draw against Olympic champions Canada, with goalkeeper Chiamaka Nnadozie the African side's hero after saving a penalty.

The Nigerian defence was solid and gave little away against a team ranked seventh in the world.

Waldrum said his side had taken note of how the Irish got players behind the ball to frustrate the co-hosts, but stressed they must also put away any chances that come their way.

"We have quality in the team, players that can score goals. We just have to make sure that when those opportunities come that we're clinical with them," he said.

They head into the match without midfielder Deborah Abiodun, who picked up a red card against Canada, but are otherwise at full strength.