Iran became the first Asian nation to qualify for November's World Cup finals in Qatar on Thursday as a goal from Mehdi Taremi earned Dragan Skocic's side a 1-0 win over Iraq in Tehran.
Taremi, who had been recalled to the squad after missing November's games following a fall-out with Skocic, struck three minutes into the second half at the Azadi Stadium to take Iran back to the top of Group A and seal their spot in Qatar.
The win delivers qualification for a third consecutive World Cup finals for the Iranians, after appearances in Brazil and Russia, and the country's sixth in total.
The Iranians should have taken a lead into the halftime break in Tehran after Ali Gholizadeh was released on goal by Alireza Jahanbakhsh, only for Iraqi goalkeeper Fahad Talib to deny the Charleroi striker.
Three minutes after the restart, however, the Iranians did take the lead. Jahanbakhsh's through ball from deep was missed by defender Ahmed Ibrahim and Porto striker Taremi raced in to score.
Jahanbakhsh, who impressed throughout, was denied a second for Iran in the 64th minute by Talib while Hossein Kanani and Saman Ghoddos also missed opportunities for the home side.
Manchester United midfielder Zidane Iqbal made his debut as a late substitute for Iraq but was unable to deny the Iranians.
South Korea moved to the verge of qualification as Cho Gue-sung's goal earned a 1-0 win over Lebanon in Sidon.
Missing injured duo Son Heung-min and Hwang Hee-chan, Paulo Bento's side were made to work for a win that moves them on to 17 points from seven games in Group A of Asia's preliminaries.
Cho scored the game's only goal when he latched onto Hwang Ui-jo's low curling cross from the left, the forward steering the ball home from close range.
Lebanon were far from outplayed, however, with brothers Alexander and Felix Melki both hitting the woodwork for Ivan Hasek's side.
The Koreans will join Iran in securing their spot at the World Cup if the United Arab Emirates fail to defeat Syria in Dubai later on Thursday.
In Group B, Australia thrashed Vietnam 4-0 in Melbourne but remain in third place in the standings after second-placed Japan downed a poor China side 2-0 at Saitama Stadium.
Only the top two nations in each of Asia's two groups are guaranteed to advance to the World Cup, with the third-placed finishers facing off in a playoff for the right to meet a South American side for a possible fifth Asian berth in Qatar.