Match ends, Australia 2, Syria 1.
Australia 2-1 Syria AET
Syria's unlikely 2018 World Cup dream is over after Tim Cahill's extra-time header saw Australia progress 3-2 on aggregate to the final qualifying tie.
Omar Al Somah gave the civil war-torn nation hope of reaching Russia when he gave them an early lead in Sydney.
But Cahill, 37, quickly equalised with the first of his two headed goals.
Syria, who drew 1-1 in the first leg, were reduced to 10 men when Mahmoud Al Mawas was sent off before Cahill nodded in Robbie Kruse's cross for the winner.
Australia will now play Honduras from the Concacaf section for a place in the finals.
Syria were given real hope of reaching their first World Cup finals when a loose Mark Milligan pass let Al Somah charge through to score a sixth-minute opener with a low left-footed shot.
But Hertha Berlin winger Mathew Leckie engineered parity for the hosts when he provided the perfect cross for former Everton midfielder Cahill's first on 13 minutes.
The introduction of Huddersfield Town midfielder Aaron Mooy from the bench was then pivotal.
Australia manager Ange Postecoglou surprisingly left the 27-year-old out of his starting line-up, but the home side were instantly improved by his presence.
Indeed it was only Syria goalkeeper Ibrahim Almeh's heroics that denied Celtic's Tom Rogic and Leckie from sealing Australia's progress in the second half.
Syria defended resolutely and admirably got to extra time, but their task became harder when Al Mawas saw red for a second booking for bringing down Kruse.
With penalties looming, Cahill produced a trademark last-gasp header to score his 50th goal for Australia - more than any other player for the country.
Yet despite being a man down, the visitors almost snatched an equaliser to take the tie to penalties when Al Somah's free-kick hit the post in the 121st minute.
'Our disappointment is very big'
Syria coach Ayman al-Hakim: "The first goal was a small mistake, not a major mistake, and the second goal was because we had 10 players.
"We studied the Socceroos very well and I think if we had stayed at 11 players and hadn't had that red card and hit the [post] at the end [it would have been different].
"But I am very proud of my boys with what they have achieved so far, and that's going to be continuing moving forward as well."
Forward Firas Al Khatib: "We were hoping to provide a smile and joy to Syrians everywhere. Our disappointment is very big."
'We keep working until we can't anymore'
Socceroos midfielder Mark Milligan: "Timmy [Cahill] worked outstandingly. That is something we have in us. We work until we cannot anymore.
"It was a loose pass [before Syria's goal]. I could have hit it a bit harder but they punished us with the quality in their striker.
"The longer the game went on, we had a good stranglehold on it. They fought with everything, they were outstanding and gave us an extremely tough match on our home soil.
"The next round will be a different match, we will have a different challenge on our hands."
Analysis: That they were in contention was remarkable
BBC Radio 5 live sports news correspondent Richard Conway:
"We went over to Syria for BBC Sport earlier in the year and spent six days in Damascus and discovered a truly remarkable story.
"Syria is in the middle of a six-year war and the team have no money because of the sanctions. Lots of Syrians have mixed emotions about supporting the team. Some, but by no means all, feel that the team rises above politics.
"The fact they were in contention for the World Cup was remarkable given what is stacked against them. They have a remarkable team spirit.
"They played their home games in Malaysia, which is a 14,000-mile round trip, and where they played the home leg of their play-off match against Australia."
Fans turn out in Syrian cities
Syrian state TV broadcasting was dominated by coverage of the country's match against Australia.
It aired special programming, with live footage of huge crowds in Damascus's Umayyad Square, Aleppo, Homs and Sweida.
Shadi Helweh, usually the channel's war correspondent and who famously covered the landmark recapture of the city by government forces in December last year, was drafted in to report on the huge crowds in Aleppo.
- 7LeckieBooked at 25mins
- 14TroisiSubstituted forRukavytsyaat 73'minutes
- 5MilliganBooked at 42mins
- 3B SmithSubstituted forMooyat 11'minutes
- 23RogicSubstituted forJuricat 96'minutesBooked at 120mins
- 4Al Baour
- 18Al Medani
- 16MidoSubstituted forHamwiahat 75'minutesBooked at 88mins
- 14Haj Mohamad
- 8Al MaowasBooked at 94mins
- 19MardikianBooked at 48minsSubstituted forOmariat 90+1'minutes
- 11Al JafalSubstituted forAl Khatibat 60'minutes
- 9Al Soma
- 10Al Khatib
- 15Al Shbli
- Ravshan Irmatov
- Shots on Target
Second Half Extra Time ends, Australia 2, Syria 1.
Offside, Syria. Ibrahim Almeh tries a through ball, but Mouaiad Al Ajjan is caught offside.
Omar Al Soma (Syria) hits the right post with a right footed shot from outside the box from a direct free kick.
Tomi Juric (Australia) is shown the yellow card.
Foul by Milos Degenek (Australia).
Omar Al Soma (Syria) wins a free kick in the attacking half.
Foul by Tim Cahill (Australia).
Firas Al Khatib (Syria) wins a free kick in the defensive half.
Tomi Juric (Australia) wins a free kick in the attacking half.
Foul by Zahir Al Medani (Syria).
Delay over. They are ready to continue.
Delay in match Robbie Kruse (Australia) because of an injury.
Trent Sainsbury (Australia) wins a free kick in the defensive half.
Foul by Tamer Haj Mohamad (Syria).
Offside, Syria. Zahir Al Medani tries a through ball, but Omar Al Soma is caught offside.
Goal! Australia 2, Syria 1. Tim Cahill (Australia) header from the centre of the box to the bottom left corner. Assisted by Robbie Kruse with a cross.
Attempt blocked. Tomi Juric (Australia) left footed shot from outside the box is blocked. Assisted by Nikita Rukavytsya.
Attempt saved. Tomi Juric (Australia) left footed shot from outside the box is saved in the bottom right corner. Assisted by Mark Milligan.
Second Half Extra Time begins Australia 1, Syria 1.
First Half Extra Time ends, Australia 1, Syria 1.
Corner, Australia. Conceded by Ibrahim Almeh.
Attempt saved. Nikita Rukavytsya (Australia) right footed shot from the right side of the six yard box is saved in the centre of the goal. Assisted by Aaron Mooy with a cross.
Foul by Tim Cahill (Australia).
Ibrahim Almeh (Syria) wins a free kick in the defensive half.
Attempt missed. Omar Al Soma (Syria) left footed shot from the left side of the box misses to the right. Assisted by Osama Omari.
Attempt missed. Matthew Jurman (Australia) header from the centre of the box misses to the right. Assisted by Aaron Mooy with a cross following a corner.
Corner, Australia. Conceded by Omar Al Soma.
Corner, Australia. Conceded by Israa Hamwiah.
Delay over. They are ready to continue.
Delay in match Jehad Al Baour (Syria) because of an injury.
Foul by Nikita Rukavytsya (Australia).
Jehad Al Baour (Syria) wins a free kick in the defensive half.
Attempt missed. Tomi Juric (Australia) header from the centre of the box is close, but misses to the right. Assisted by Mathew Leckie with a cross.
Substitution, Australia. Tomi Juric replaces Tomas Rogic.
Second yellow card to Mahmoud Al Maowas (Syria) for a bad foul.
Robbie Kruse (Australia) wins a free kick on the left wing.
Foul by Mahmoud Al Maowas (Syria).
Attempt saved. Nikita Rukavytsya (Australia) left footed shot from the left side of the box is saved in the centre of the goal. Assisted by Matthew Jurman.
Tomas Rogic (Australia) wins a free kick in the attacking half.