Bernd Stange’s side showed improvement but it was not enough against a quality opponent, as the German suffered defeat in his first competitive game in charge.
The Lions started the game brightly as they pressed their opponents hard, although the visitors didn’t take long to adapt as they moved the ball quicker to keep possession.
Shahfiq Ghani tried his luck with a 30-yard effort that bounced wide in the 10th minute, before Eid Al-Farsi drove his shot from a similar distance into Izwan Mahbud’s arms a minute later.
It was Oman who took the lead in 14th minute through a well-worked move. With the Singapore defence on the back foot, Qasim Said raced in from the blind side on the right to latch onto a through ball before drilling a fine finish into the far corner.
The Singapore players did not let their heads down but they struggled to create chances from open play, with the visitors happy to sit back and try to catch their opponents on the break.
The home side’s best opportunity of the half came near the half hour mark when skipper Shahril Ishak was tripped just outside the box. Qiu Li stepped up and floated his freekick just past Faiyz Al Rusheidi’s post, with the goalkeeper looking beaten.
A one-goal deficit would not have been the worst of scorelines for Singapore to take into the break, but Paul Le Guen’s men struck again just before half-time.
Another slick, quick move saw Abdulaziz Al-Muqbali set up Al-Farsi for the midfielder to smack a 25-yard daisy-cutter into the bottom corner that left Izwan with no chance.
It was nearly 3-0 six minutes into the second half when Al-Farsi got to a Raed Saleh pass and squared the ball for Qasim, but the forward miscued his kick with only Izwan to beat.
Shahril appeared to be ploughing a lone furrow upfront at times as the midfielder did well to hold on to the ball on occasions, but was eventually crowded out as he failed to receive the necessary support from his teammates.
Oman were content to push forward only on the counter-attack but it was effective as they looked dangerous every time they did, with Al-Muqbali prodding Raed’s cross just wide at the near post in the 78th minute.
Two minutes from the end, substitute Ismail Al-Ajmi spurned another opportunity to add a third as he nodded Saad Al-Mukhaini’s corner wide from an unmarked position.
That was the last chance of the game as the Omanis notched a deserved second consecutive win in Group A with a degree of comfort, with Stange left to reflect on a performance that showed how far behind the Asean champions are still at his level.