The Socceroos dominated their opponents at Stadium Australia, as goals from Matt McKay, Robbie Kruse, Mark Milligan and Tomi Juric sealed a comprehensive victory at Sydney's Stadium Australia.
Apart from some early pressure on the Australia goal - with Mat Ryan pulling off an excellent diving save to keep the visitors out - Oman had no answer to the hosts.
The result means Australia are assured of their place in the quarter-finals, while Oman's hopes of reaching the last eight are now over.
"They were far better than us in each part of the game," Le Guen said.
"We were not able to cope with such pace three days after our game against South Korea.
"They were too good for us. It's because they have the power and the fitness. Of course they had four days recovery but even with three days it could've been the same [result].
"That is why they are favourites for the competition.
"It was too much for us. We have to recognise this. Australia have more power on set pieces it’s an opportunity for them."
This Australia performance was vastly different to the one in March 2013 when they laboured to a 2-2 draw with Oman at the same venue under previous coach Holger Osieck.
"It seems to me they have power, they have legs, they have dynamism. It's a good balanced team,” added Le Guen.
"Some experienced players they have, but also some who have legs. They have refreshed the team and I think it's a good thing."
