SINGAPORE - The Lions will be licking their wounds while on their travels across the Causeway after they squandered a 2-0 lead to suffer a 4-2 defeat by Thailand in an Asean Championship match at the National Stadium on Dec 17.

The Lions' last-four hopes will now go down to the final group match against Malaysia at Bukit Jalil National Stadium, where Singapore will need to avoid defeat to reach the last four of the biennial competition for only the second time since winning the title in 2012. 

The Lions have six points from three matches and sit second in Group A. They began the campaign with a 2-1 victory over Cambodia at the National Stadium on Dec 11 before a 3-0 win over Timor-Leste in Vietnam three days later.

Lions coach Tsutomu Ogura spoke about a tale of two halves, saying: "The first half I think was the best 45 minutes (I have overseen). Players were not scared, not afraid, built up from the back. The opponents were also a little bit confused."

But Ogura added that the team could not keep up their good start after the break and lamented the team's inability to hold on to possession. The Japanese tactician added of the second period: "They (Thailand) were more aggressive... (We were losing) a little bit more and more pace to the opponents... (We must have) a stronger mentality."

Ogura said he will return to the team hotel to start analysing their next opponents, and the players' focus also seemed to have already shifted to Bukit Jalil as local media were told the team would not be available for post-match interviews.

Perhaps the players were still reeling from giving up a two-goal lead at home.

Thailand coach Masatada Ishii, meanwhile, said: "The players fought till the final whistle. Singapore were a good team and the two goals they scored were hard to defend.

"At half-time, we watched clips of the first half and we fixed our mistakes and looked at how we could limit the Singapore attack."

The evening had began brightly for world No. 161 Singapore when they stunned 97th-ranked Thailand after 34 minutes, courtesy of two moments of individual brilliance from Shawal Anuar and Faris Ramli.

But shoddy defending allowed Thailand to find their way back into the tie and eventually bag all three points to seal their place in the last four as group winners with a game to spare.

Cambodia and Malaysia are also still in contention for the other semi-final spot. Cambodia, who beat Timor-Leste 2-1 in Phnom Penh in the earlier game on Dec 17, are third with four points from three matches, level on points and goal difference with fourth-placed Malaysia.

Teams level on points are first differentiated using head-to-head records and then goal difference.

A crowd of 22,611 - mostly in red and white bar a section of about a hundred blue-clad Thai fans - were in full voice for the first half and the Lions responded accordingly, with two goals that will be watched multiple times over the next few days.

The National Stadium had already been buzzing before kick-off as the crowd gave players from the 1994 Singapore "Dream Team" who won the Malaysia Cup exactly 30 years ago a standing ovation when they were paraded on the pitch.

The home support would again collectively get off their seats in the 10th minute, when Shawal controlled a long hoof from Izwan Mahbud with a deft first touch before unleashing a shot that was beyond the reach of Thai goalkeeper Patiwat Khammai.

The replay of the goal on the big screen produced a collective "oooh" from the crowd. They would be treated to another moment of magic in the 34th minute, when Faris cut in from the left flank and curled in an effort from around 20 metres out.

The visitors hit back in first-half stoppage time when Anan Yodsangwal picked out Patrik Gustavsson to pull one back. The goal just before half-time gave the Thais momentum going into the second half, which they duly used to their advantage.

In the 52nd minute, the Lions' loose marking once again saw Suphanat Mueanta head home a cross.

The Thais then looked to have completed the comeback in the 71st minute when Pansa Hemviboon headed in from a corner - only for Bahraini referee Ismaeel Habib to chalk off the goal with the help of the video assistant referee (VAR) due to a foul on Izwan.

But the Thais kept knocking and in the third minute of added time, they found the breakthrough when Peeradon Chamratsamee got on the end of a cross to prod home from close range.

The goal was initially flagged for offside but, after a long wait, the referee signalled that it would stand after VAR deemed that Peeradon had indeed been onside.

The Thais got their fourth in the 15th minute of stoppage time through Teerasak Poeiphimai as the majority of fans made their exit.