With only the group winners guaranteed automatic qualification, Syria joined Japan three points clear at the top of Group C with just two games remaining after Al Salih's strike ended the Blue Samurai's 100% start to the campaign.
After Japan's Yuya Osako could only divert Mohammed Fares' 19th minute free-kick into his own net at King Abdullah International Stadium, Kensuke Nagai pulled Japan level in first-half stoppage time with a superb first-time angled strike.
But with time running out, Al Salih's speculative 35-yard strike looped over Japan goalkeeper Shuichi Gonda as Syria gained revenge for their last-gasp 2-1 defeat in Tokyo in November, with their third win of the campaign enough to edge ahead of Japan at the top of the table.
With the three runners-up entering a play-off in Vietnam at the end of March for the right to face Senegal for a place at the Olympic Games, Bahrain sit just three points further adrift after Husain Farhan netted a superb solo goal with two minutes remaining to claim all three points against Malaysia.
Ahmad Hazwan Bakri appeared to have earned Malaysia a first point of the campaign after cancelling out Mohamed Tayeb Al Alawi's 25th minute opener with five minutes remaining at the National Stadium in Manama, only for Farhan to hit back for Bahrain three minutes later.
Syria next travel to Manama on February 22, while Japan take on Malaysia in Kuala Lumpur.
In Group A, Korea Republic remained a point clear of Oman at the top of the table after Kim Bo-kyung struck in stoppage time in Dammam to earn a 1-1 draw against Saudi Arabia following an entertaining contest at the Prince Mohammed Bin Fahad Stadium.
Omar Suktan Khudari's 60th minute opener looked to have handed Saudi Arabia a first win of the campaign, until Kim acrobatically maintained Korea's unbeaten record in the first minute of added time and keep his side firmly in the hunt for London 2012.
And with Oman sharing a 2-2 draw with Qatar, Korea maintained their slender advantage at the top of the table ahead of their trip to Muscat later this month.
At Al Sadd Stadium, Fahad Al Bulushi opened the scoring for Qatar after 26 minutes before Abdulaziz Al Maqbali pulled Oman level eight minutes later.
Hussain Al Hadhri completed the turnaround for Oman after 76 minutes only for Hasan Al Haydos's penalty with four minutes remaining to pull Qatar back on level terms.
The drama, though, was not over as Qasim Said failed to convert from the spot two minutes later as Oman missed the chance to move two points clear at the top of the table.
Qatar will look to record a first win of the campaign in just over two weeks when Saudi Arabia make the short trip to Doha for the penultimate round of fixtures.
Finally, Uzbekistan took a huge step towards securing a first appearance at the Olympic Games after beating Australia 2-0 in a snow-covered Tashkent.
With the temperature at JAR Stadium dropping to -12 C despite the afternoon kick-off, Kenja Turaev and Oleg Zoteev scored in either half as Uzbekistan moved three points clear of the United Arab Emirates at the top of the Group B.
Nasaf striker Turaev, who scored and set-up another as Uzbekistan beat Iraq 2-0 at home on Matchday One, sent a dipping half-volley past Australia goalkeeper Mathew Ryan after 27 minutes before the Central Coast Mariners custodian was again left helpless as Zoteev sealed the win in spectacular style with five minutes remaining.
The UAE moved into second place after beating Iraq 1-0 in Doha thanks to Ahmad Ali's third minute strike, while winless Australia slipped to the foot of the table after extending their scoreless streak to four games.
On Matchday Five, Iraq entertain Uzbekistan in their adopted home of Doha, while Australia face the UAE in Abu Dhabi.