With Iran and Japan having already booked their places at next year's finals, Australia, Saudi Arabia, the United Arab Emirates, South Korea, Syria, Uzbekistan and China all jostle for the remaining tickets.
The top two teams from both Asian groups qualify directly, with the third-placed sides to battle each other for the right to enter an intercontinental playoff against a side from the CONCACAF region.
Australia's fate continues to rest in the hands of the Japanese. The Socceroos take on Thailand in Melbourne knowing victory may not be enough to ensure an automatic place should Saudi Arabia defeat the Samurai Blue in Jeddah.
"There's no more important game that I can recall over the last 10 years since we've been in Asia for qualification," Australia's stand-in captain Mark Milligan said of the Thailand game in comments on Football Federation Australia's website (footballaustralia.com.au),
Australia are third in Group B and trail Saudi Arabia on goal difference, meaning wins for both teams could see the Saudis seal their spot in Russia and Ange Postecoglou's team head into the playoffs.
The United Arab Emirates, currently fourth in the group following their win over the Saudis on Tuesday, also retain a mathematical hope.
But they would need a big win over Iraq plus heavy defeats for both Australia and Saudi Arabia to claim third and a route through the playoffs.
Group A, meanwhile, has a four-way tussle for the two remaining spots that could lead to the World Cup.
Second placed South Korea can qualify directly for an eighth successive World Cup appearance with a win over fourth-placed Uzbekistan in Tashkent.
A defeat, however, could be catastrophic for the South Koreans if third-placed Syria can upset Iran away.
That could put Syria, who are ahead of Uzbekistan on goal difference, in second place and grant them automatic passage to Russia.
A win over Iran, who remain unbeaten in this phase of qualifying, would be a stunning achievement by a side that has been forced to play all their home games away due to the civil war at home.
But Iran coach Carlos Queiroz has stressed his team will not ease up despite having already qualified for a fifth World Cup appearance.
"To think that these players are going to make it easy against Syria is to not know them, their professionalism, character and pride serving the Iranian nation," said Queiroz.
On the fringes are Marcello Lippi's China, who could yet steal a place in the playoffs if they beat Qatar away and both Uzbekistan and Syria lose.
(Editing by Ian Ransom)
