United States star Christian Pulisic appears in serious doubt to face the Socceroos, with coach Mauricio Pochettino stopping short of confirming the attacker's availability for the blockbuster clash.
And the US coach says his charges must match Australia's "mindset" to get a crucial three points that could determine who tops Group D.
Pulisic hasn't trained with his teammates all week, including on Thursday, as he deals with a left calf issue.
The 27-year-old dubbed 'Captain America' picked up a calf knock in training last week and was withdrawn at halftime of the US's 4-1 win over Paraguay after starring in the first half.
Pochettino said he would meet with medical staff on Thursday before making a decision on whether Pulisic features on Friday (5am Saturday AEST) at Seattle Stadium.
