Qatar's goalless draw against Gulf neighbours Bahrain means the 2022 World Cup hosts must travel to Iran in their final Group E game hoping to avoid defeat to seal their passage to the final round of Asian qualifying for the 2014 World Cup.
The 0-0 stalemate left Qatar in second place in the group on nine points, two behind leaders Iran, who routed Indonesia 4-1 in the earlier game, and Bahrain third with six points.
Bahrain now need to beat basement boys Indonesia, who have lost all five of their qualifying matches, in their final game, scheduled for February 29, and needing Iran to do them a favour and inflict a first loss of the campaign on the Qataris to stand a chance of progressing.
In Group D, Oman gave themselves a fighting chance of booking their place through to the next round when they held Saudi Arabia to a 0-0 draw in Riyadh on Tuesday night. Oman, who had given themselves hope of qualifying with a 1-0 home win over Australia on Friday, are third in the group on five points, one behind the Saudis on six, with Oman facing Thailand, who technically can also still qualify should they win in Muscat and Australia beat Saudi in their final match.
Australia secured qualification outright when Brett Holman scored the sole goal for Australia in the 77th minute, heading in a pinpoint cross from Brett Emerton, to give them a 1-0 win in Thailand.
The result ensured the Socceroos will finish in top spot in Group D.
The game was played at Suphachalasai Stadium in downtown Bangkok, as the larger-capacity Rajamangala Stadium is being used as an evacuation centre for victims of Thailand's floods.
In Group C, North Korea beat Japan 1-0 in a tempestuous qualifier, the result largely academic, with the visiting Blue Samurai already through to the final qualifying round for 2014.
Pak Nam-chol headed the winner in the 50th minute, and the final whistle sparked wild celebrations at Pyongyang's Kim Il-sung stadium despite the fact North Korea had already been eliminated.
"We didn't do anything right for 90 minutes," Yasuyuki Konno, the Japan defender, said. "They dominated us. We were pathetic."
Under the gaze of a giant portrait of North Korea's "Eternal President" Kim, Japan's national anthem was drowned out by boos before a fractious match.
Matches between the two invariably take place against a backdrop of political tensions over the Second World War, North Korea's nuclear ambitions and the kidnapping of Japanese citizens.
Asian champions Japan, who have 10 points from five matches, lost for the first time in 17 games under Italian coach Alberto Zaccheroni.
Victory also gave North Korea payback for a 1-0 injury-time defeat in Japan in September.
Uzbekistan - who beat Tajikistan 3-0 on Tuesday - will join Japan in the final round of qualifiers from Group C.
China won 4-0 away to Singapore, but their chances of qualifying disappeared when Iraq comprehensively beat Jordan 3-1 away with both teams now qualifying from Group A.