Cahill was sent off in the 56th minute for a challenge on German midfielder Bastian Schweinsteiger at a time when the Socceroos were already trailing 2-0.

The Everton star broke down in front of the media after the game after Schweinsteiger approached Cahill in the media mixed zone and told him he should not have been sent off.

Cahill then described the situation as 'one of the saddest moments of my footballing career to be in this position'.

While Cahill will be automatically suspended for the Socceroos' next clash against Ghana in Rustenberg on Saturday, there is a possibility that FIFA could rub him out for two matches which would also rule him out the final group game against Serbia.

And given Cahill has been by far Australia's most prolific scorer in recent times and the Socceroos need to win both games to make it through to the round of 16, a two-match suspension would be a disaster for the country's hopes at this World Cup.

Football Federation Australia was awaiting official confirmation from FIFA overnight in South Africa as to the length of Cahill's ban although it is expected to stay at one-match given that many felt his tackle was only deserving of a yellow card in the first place.

However Neill said it would be laughable if Cahill received a two-match ban as a result of his sending-off.

"He will miss one at least anyway because it can't be appealed but if he misses two, then they (FIFA) have to ask questions of themselves," he said.

Neill had no doubt the sending-off of Cahill was harsh.

"When you look at it (the tackle) on TV he has got in to make a tackle and realised he is not going to get there and pulled out and he actually clips him with his knees with his two heels tucked up and his arms in the air as if to say I don't want to touch him," Neill said.

Neill said despite the Cahill sending-off and the humiliating defeat - Australia's worst ever at the World Cup finals - the spirit remained high in the camp while he remains convinced the Socceroos can still qualify for the knockout stages by beating both Ghana and Serbia.

"The Germany game was never going to be the one to decide whether we were going to get out of the group or not," he said.

"Anything we got out of that game (against the three-time winner) was always going to be a bonus although losing 4-0 was not the way we planned it but the next two games were always going to be the games we had to win (to make it to the second round)."

"I am still very proud (of the team) we have taken on one of the best teams in the world and we have lost so it's nothing to be ashamed of and now we have to win the next two games and we believe we can."