The result left Indonesia third in Group A on seven points, with only a win enough to take them through. Vietnam topped the group on 10 points and Singapore advanced on eight.
Video circulated by the X account Secondline Squad and reported by Tribunnews shows a supporter telling coach John Herdman he should be ashamed as the squad walked to the away section.
Midfielder Thom Haye answered back, twice asking the fans whether they had seen what the referee did.
Pattynama, the Netherlands-born left-back now with Persija Jakarta, then moved toward the stand and Raven stepped in to stop him.
Tribunnews described Raven’s hand as touching or slapping Pattynama’s head, while Bolasport reported he was caught on camera slapping the defender.
Captain Rizky Ridho stayed at the stand to hear the supporters out and apologized afterwards, telling reporters the squad was disappointed, according to Tribunnews.
Singapore had been reduced to 10 men in the 55th minute when the Omani referee showed midfielder Song Ui-young a second yellow card for elbowing Ivar Jenner, only to cancel the cards for both players after reviewing the pitch-side monitor.
The reversal was possible because of a revision to the Laws of the Game for 2026/27, in effect since the World Cup, which lets VAR review a red card issued for a second caution, Bola.com noted. The video official was Thai referee Pansa Chaisanit, assisted by Jun Mihara.
Indonesia had appealed unsuccessfully for a penalty in the 20th minute when striker Mitchell Baker went down in the box. Herdman declined to revisit any of it afterwards, telling Tribunnews that Singapore had been the stronger side.
Ragnar Oratmangoen had put Indonesia ahead in the 47th minute, converting Dony Pamungkas’s cutback at the second attempt, according to tournament organizer ASEAN United FC.
Ilhan Fandi levelled in the 66th when a lofted ball caused confusion between Ridho and goalkeeper Cahya Supriadi.
Football Association of Indonesia chairman Erick Thohir announced a full evaluation of the campaign hours after the final whistle, saying the review was aimed at preparing the team for the tournaments ahead, the Jakarta Globe reported.
Indonesia had opened with a 5-1 win over Cambodia and a 3-0 win over Timor-Leste, though they broke the deadlock in the second match only in the 74th minute through Pattynama. A 0-3 loss to Vietnam in Bogor on Aug. 3 then left them needing a victory in Singapore.
Herdman named 12 naturalized players in his squad and started seven foreign-born players against Singapore, with Transfermarkt valuing the Indonesian squad at roughly $11.13 million, the highest at the tournament.
Several Europe-based players were unavailable because the ASEAN Championship sits outside the FIFA international match calendar, leaving their clubs under no obligation to release them.
Indonesia have reached six finals since the competition began in 1996 without winning it, and went out in the group stage in 2024 as well, under then-coach Shin Tae-yong.
Singapore host the Group B winners in the first leg of the semifinals on Aug. 15, chasing a fifth regional title.
Indonesia return in September at the inaugural FIFA ASEAN Cup, a separate FIFA-run tournament running from Sept. 24 to Oct. 3, with Indonesia hosting the Premier Division and Hong Kong the Challenge Division.