South Korea edged a tense encounter against Uzbekistan and Australia finally hit form with a 4-0 win over Jordan as the regional giants took big strides towards next year's World Cup on Tuesday.
South Korea's 1-0 victory, courtesy of a first-half own goal, puts them one point clear in Group A ahead of Iran, who outclassed bottom side Lebanon 4-0 in Tehran.
It all sets things up for a thrilling denouement next week with the Koreans hosting Iran in their final game in what should be a highly charged atmosphere in Ulsan.
Third-placed Uzbekistan, still capable of making history as the first Central Asian country to reach the World Cup, are at home to 2022 World Cup hosts Qatar, who are out of contention.
Only the top two teams in Asia's two final qualifying groups win an automatic spot, with the third-placed countries entering a play-off. Group B winners Japan are the only team to book their ticket to Brazil so far.
Meanwhile Australia eased their jitters after a lacklustre campaign with a win which leaves them in Group B's second automatic qualifying spot ahead of their final game at home to Iraq next week.
At Melbourne's Docklands Stadium, young winger Robbie Kruse set up veterans Mark Bresciano and Tim Cahill, and then grabbed a goal of his own before skipper Lucas Neill rounded off the scoring with his first international goal.
Australia's coach Holger Osieck said he felt "pretty sure" Australia now had the momentum to beat Iraq and get to Brazil. Jordan and Australia had been locked on seven points each before Tuesday's game.
"You can never dream of a score like 4-0 but I think the overall performance was excellent," he said. But the German warned there would be no celebrations yet, noting: "We have to focus on the next game."
After a cagey opening in Seoul, Anzur Ismailov's long shot forced a save from South Korea's Jung Sung-Ryong, and reigning Asian player of the Lee Keun-Ho was guilty of a terrible miss when he sliced an easy shot wide from close range.
Uzbekistan's Ulugbek Bakaev drew Korean 'keeper Jung into action again with a shot but he also passed up a golden chance when he met Server Djeparov's cross unmarked at the far post, but planted his header high and wide.
After 41 minutes, imposing Korean striker Kim Shin-Wook's knock-down fell to Lee Myoung-Ju, but Uzbek custodian Ignatiy Nesterov dived low at his feet to deny the debutant midfielder.
However, the Korean pressure told just a minute later when Kim Young-Gwon's arcing cross from deep on the right fell to the unfortunate Akmal Shorakhmedov, who could only direct it into his own net.
After the break, Timur Kapadze fired over in a strong spell for the visitors but South Korea gradually regained control and had the best chances of the second half.
"I felt this match would come down to a single goal," said South Korea's coach Choi Kang-Hee. "We were able to win because our players never lost their concentration."
Jordan had described the game against Australia as the biggest in their history, but they were disappointing in Melbourne and never recovered after falling behind on 15 minutes.
As the referee waved advantage after a foul on the right touchline, Kruse galloped to the byline and cut back his cross for Bresciano, who stabbed home an easy shot from close range.
Germany-based Kruse was again the provider for Cahill's header for 2-0 just after the hour mark, and he scored the goal of the game when he turned and nutmegged a defender and swept home on 76 minutes.
Eight minutes later, former Premier League defender Neill got in on the act when he nodded his first goal in 91 appearances for the Socceroos.
"Wonderful," said Kruse, 24, who is headed from Fortuna Dusseldorf to Bayer Leverkusen and Champions League football next season.
"To get the win was excellent... it puts us in a good position going into the next game." He added: "It was fantastic to get four goals, and we could have had a few more."
In Tuesday's other Group B game in Doha, already qualified Japan ended Iraq's hopes with a 1-0 win after Shinji Okazaki scored in the 89th minute.