Australia eye Sam Kerr return in Women's World Cup last 16
The Matildas captain has yet to see any minutes at the tournament after a calf injury sustained before their opening game.
But she took a big step towards her recovery by resuming training with a ball on Saturday and could finally be thrust into action.
"We had a nice moment with the team yesterday to see her back with her boots on and touching the ball and being with the team in training," said Gustavsson.
"It was a very good feeling for Sam, her teammates and me.
"She is a player we will talk about tonight to see how many minutes would be most suitable, looking at 90 minutes and extra-time and how do I get the best out of Sam Kerr in a game plan tomorrow," he added.
Australia didn't need Kerr's goal-scoring prowess in an impressive 4-0 win over Olympic champions Canada in their final must-win group game, with Hayley Raso, Mary Fowler and Steph Catley all hitting the mark.
The raucous spectators also played a part and Gustavsson said a potential 70,000-plus crowd at Stadium Australia in Sydney would again be crucial to get them into a quarter-final against either France or Morocco.
"The one thing I want to emphasise is the support from the stands," he said. "The way the supporters have carried us through these games, the players feed off that."
Australia beat Denmark 3-1 in a friendly last year, but Gustavsson is wary of the threat posed by a side that pushed European champions England hard in a 1-0 group stage loss.
"I've been very impressed, so we need to be humble and realise that we need to focus in every single second tomorrow and be as solid defensively as we were against Canada," he said.
"They have threats left and right and in very different ways. It's going to be tough and we need to bring our A game."
Other than Kerr, Australia also have injury worries, with both striker Kyah Simon and winger Cortnee Vine to be assessed before kick-off.
Follow Australia's match against Denmark here with Flashscore.
