Despite a fifth international goal from Faris Ramli, Singapore suffered a 3-1 defeat away to Qatar at the Jassim Bin Hamad Stadium in an international friendly in Doha on Thursday night, stretching their winless streak to 10 matches.
Faris strike gave the Lions a glimmer of hope after Qatar went two goals up through an Almoez Ali brace.
However, that proved to be a mere consolation as substitute Ahmed Alaadin's late penalty would seal victory for the 2022 World Cup hosts.
Singapore have yet to win since beating Cambodia 1-0 in a friendly in November 2016.
Qatar, 77 places higher than Singapore in the FIFA rankings at 85th in the world, dominated the first half-hour, but were unable to put their chances away.
Captain Hassan Khalid cut in from the left before firing wide on four minutes.
Six minutes later, Abdulkarim Salim was denied in a one-on-one opportunity with Singapore keeper Hassan Sunny.
Ali then volleyed over on 20 minutes before Boualem Khoukhi fired wide after a barnstorming run through the middle two minutes later.
The home side deservedly found the breakthrough in the 39th minute, with Ali capitalising on a Singapore defensive error to slot past a helpless Hassan.
Singapore could have levelled matters just before the break after Fazrul Nawaz and Khairul Amri combined well on the edge of the box. But the former's shot was denied by Oumar Barry in the Qatar goal.
Qatar turned it on again at the start of the second half, doubling their lead on 52 minutes.
Ismail Mohamed peeled away from his marker on the right wing, before producing a delicious cross for Ali to nod home his second of the night.
Against the run of play, Singapore would pull one back a minute later. Faris fired home from just inside the area for his fifth goal in 35 international appearances.
The Lions were growing in confidence, and had the ball in the net again on 58 minutes. But Fazrul's header from two yards out was ruled out by the offside flag.
Qatar could have restored their two-goal advantage eight minutes later, but Khoukhi was denied by a stunning Hassan reflex save.
Singapore were still in with a shout and should have netted the equaliser on 78 minutes. However, Daniel Bennett, earning his 139th cap three months before his 40th birthday, could only nod wide from Shahdan Sulaiman's corner.
That miss proved costly as Qatar settled the game three minutes later, with Alaadin converting from the spot after being fell by Hassan in the area.
Singapore will now turn their attention to the crucial Asian Cup qualifying game against Turkmenistan away in Ashgabat on Oct. 10.
A loss could spell the end of their hopes of making the continental tournament for the first time since hosting it in 1984.
Qatar: Oumar Barry (GK), Ahmed Abdelrahman, Musaab Khidir Mohamed, Hassan Al-Haidos (C), Karim Boudiaf (Abdulaziz Hatim 72'), Pedro Miguel Correia, Boualem Khoukhi (Ali Asadalla 72'), Ismail Mohamed (Akram Hassan 62'), Abdulkarim Salim (Tarek Salman 46'), Almoez Ali (Ahmed Alaadin 62'), Assim Madibo (Ahmed Mohamed 62')
Singapore: Hassan Sunny (GK), Madhu Mohana, Daniel Bennett, Zulfahmi Arifin (Irfan Fandi 48'), Faritz Hameed, Hariss Harun (C) (Izzdin Shafiq 67'), Shahdan Sulaiman, Hafiz Sujad, Fazrul Nawaz (Ikhsan Fandi 59'), Khairul Amri (Safuwan Baharudin 52'), Faris Ramli (Yasir Hanapi 73')