Qasim Said eased past a static home defence to fire Oman into a 15th-minute lead with his fellow midfielder Eid Al-Farsi blasting a low drilled shot from 22 metres to double the advantage on the stroke of halftime.
The home side wilted in the second half with Oman guilty of wasting several chances to improve their goal difference in the four-team group, also featuring Syria and Jordan, where two sides will qualify for the finals in Australia in 2015.
"I think we did the job, it was vital to win and we did it," Le Guen, who had been concerned before the game that his players would still be feeling the effects of fasting during the Islamic holy month of Ramadam which ended last week, told reporters.
"During the first half we were average, not many chances but efficient.
"I was afraid of the context, the artificial pitch. But we prepared well ... the players accepted to leave Oman before Eid which is not easy for them and I want to thank them for the effort."
Syria host Jordan in Iran on Thursday in the other Group A match in the second round.
The teams are back in Asian Cup qualifying action in October along with the other 16 sides trying to reach the finals in Australia where the hosts, holders Japan and South and North Korea all have places and do not need to qualify.
- Sports & Recreation
- Paul Le Guen