In the early stages Iran, even without their Spain-based stars, were by far the better side, and duly took a two-goal lead within 13 minutes.
For the first, Nigerian-born stopper Precious Emuejeraye felled X in the box, allowing Hadi Aghili to step up and convert a spot-kick for the Iranians.
Minutes later Mehrzad Madanchi made it 2-0 to the visitors as Mustafic Fahrudin misplaced a pass on the edge of the box, allowing the Al-Ahli midfielder a chance to barrel the ball home.
Singapore looked hopelessly out of their depth at this point, but eventually they managed to strike a comeback.
Cult forward Noh Alam Shah reduced the deficit after a brief period of pressure with a superb diving header from the edge of the area that left the Iranians stranded.
In fact the Lions then went on to enjoy the best of the first period before the half time whistle sounded.
Shortly after the restart Khairul Amri's corner met Shaiful Esah for a header that cannoned back off the crossbar, but eventually Iran's quality was to tell.
Some disorganised defending from Singapore allowed Iran to strike on the break: a brilliant three-man move culminated in a cheeky lob by veteran defender Rahman Rezaei.
From there Iran were comfortable in their lead and went on to qualify for the tournament in Qatar in 2011. Singapore eagerly await the results of other matches.