Australia captain Mile Jedinak was one of the men who sent a letter to Federation Internationale de Football Association to permit him to play.
A stunning Andre Carrillo volley gave Peru their first World Cup goal in 36 years before captain Paolo Guerrero grabbed a second as the Andean nation condemned Australia to a 2-0 defeat in Sochi on Tuesday and an early exit from Russian Federation.
Edison Flores nearly added a third goal on the counter when he crashed a low drive onto the post from the edge of the box in the closing minutes, but the offside flag was raised and there was to be no final flourish for Peru.
"We have just been told that (Farfán) is already aware, that he can now move his legs and hands, thank God he is out of danger, he may travel with us, but I do not think he will play".
Back at the World Cup for the first time since 1982, Peru isn't leaving Russian Federation empty handed.
However, many Australian fans will be disappointed not to see Cahill, the 38-year-old who is his country's record goal-scorer.
Peru opened the scoring through Andre Carrillo, who lashed home a superb left-footed volley from the edge of the area across the diving Mat Ryan, who had no chance.
They made up the majority of the 44,073 crowd in sauna-like conditions by Russia´s Black Sea coast, and the stadium exploded when Carrillo scored their first goal at a World Cup since 1982. As the minutes progressed, the counter was working as Peru was giving away the ball in crucial places, allowing its opponent to threaten, who was clearly looking for a win knowing its hope to qualify to the knockout stage was still alive.
France fullback Djibril Sidibe was emphatic that Les Bleus wanted to retain top spot in the group and would bring their best against Denmark, music to the ears of Australia.
Australia leaves consoled by decent performances even though it didn't get the points to show for it. As far as his replacement, the coach offered only that he would "choose the player that will have the most chance to get the result".
That is the only change to the Socceroos team following their 1-1 draw with Denmark in Samara in their last game.
Having steered Australia through the hard work of qualifying, Postecoglou quit in November, leaving a team questioning its identity before their fourth straight World Cup. It's last World Cup victory was a 4-1 result against Iran in the first round of the 1978 tournament in Argentina. Ghana did it from 2006-2010.