World Cup qualifiers Iran overcame a stubborn defensive effort by Thailand to claim a 2-1 win in Tehran but Jordan, hoping to join them in Brazil next year, played out a drab goalless draw at home to Oman.
Elsewhere, Ali Mabkhout scored a hat-trick as United Arab Emirates routed Hong Kong 4-0 to maintain their 100 percent record in Group E and Uzbekistan overcame Vietnam 3-1 in Tashkent.
Wednesday marked the halfway stage of the five qualifying groups with 11 places still up for grabs after a number of draws left the identity of the finalists in Australia still undecided.
In Group A, Singapore were expected to offer little resistance to 2011 Asian Cup competitors Syria but Khairul Amri and substitute Gabriel Quak scored second half goals as the hosts grabbed all three points on their plastic pitch.
A brilliant solo effort by forward Reja Rafe proved too little too late for Syria as the home side deservedly held on to move up to third and one place off the qualifying positions for Australia.
"It is not a good result to beat Syria 2-1, it is a very good result. It was a hard fight," Singapore's German coach Bernd Stange told reporters.
However, the much-travelled coach held little hope of overtaking Jordan or Oman to claim one of the two berths from the pool or the best third place position across the five groups.
"We don't care for the next matches we have in this qualification, we have to be realistic. Today we are very proud that we could achieve such a performance and of course the result was very good."
Oman lead the group on seven points after their goalless draw against Jordan, who moved on to five with Singapore on three and Syria last on one.
China have enjoyed a resurgence under caretaker boss Fu Bo following the dismissal of former Spain and Real Madrid coach Jose Antonio Camacho but he could not prevent them throwing away the lead to draw 1-1 in Indonesia.
Wu Xi gave the visitors a deserved lead in the 36th minute of a first half they dominated but in the muggy temperatures the Chinese tired and the hosts made them pay with captain Boaz Solossa smashing home a brilliant volley in the 68th minute.
"I made a game plan for each half. I knew that China would suffer with the hot weather and it worked," Indonesia coach Jacksen Tiago said.
China now have four points in Group C with leaders Saudi Arabia taking on Iraq later on Tuesday.
In Group B, Iran went top after they overcame the Thais, while Lebanon (four points) and Kuwait (five) played out a 1-1 draw in Beirut.
Two goals in three minutes from defender Jalal Hosseini and forward Reza Ghoochannejhad put hosts Iran clear with 20 minutes left only for Teerasil Dangda to pull one back in the 80th minute.
There were no such narrow margins in Group E where the UAE made it three wins from three thanks to Mabkhout's hat-trick with Walid Abbas completing the rout in the final moments.
Uzbekistan moved second in the group on four points, level with Hong Kong, after their 3-1 win over Vietnam.
In Group D, Bahrain lead the way on seven points after they failed to win for the first time following a 1-1 draw in Kuala Lumpur against Malaysia.
Abdullah Ahmed Saleh put the visitors ahead in the first half before Norshahrul Idlan Talaha deservedly equalised 20 minutes before the end as the Malaysians came close to snatching an upset win.
World Cup 2022 hosts Qatar are second in the group on six points after they thrashed bottom side Yemen 6-0 on Sunday. Malaysia have four points.
Defending champions Japan have already qualified for the tournament along with hosts Australia and South Korea courtesy of their top three finishes four years ago in Qatar. North Korea have also booked a spot after winning the 2012 Challenge Cup, a tournament for developing Asian nations.