Australia qualified for next year's World Cup in North America while Oman ended Palestine's hopes of a first appearance at the finals with a last-gasp draw on Tuesday.
Tony Popovic's Socceroos, who went into the third round's final match day heavy favourites to progress, defeated direct rivals Saudi Arabia 2-1 in Jeddah to seal the second automatic qualification spot in Group C.
Saudi Arabia must instead make do with a place in the fourth round, alongside Indonesia. Japan had already secured top place in the group.
"We've built a good foundation now and we want to really get better, kick on and try and do something special at the World Cup," said Popovic.
Herve Renard's Saudi side went into the decider at King Abdullah Sports City Stadium knowing only a win by a five-goal margin would be enough to usurp Australia in second.
The hosts were given the perfect start when Abdulrahman Al-Aboud opened the scoring 19 minutes in.
The visitors pulled level just before half-time through Connor Metcalfe's left-footed strike.
Australia were soon ahead, when three minutes into the second half Mitch Duke met Martin Boyle's cross to head home from close range.
Goalkeeper Mathew Ryan then saved Salem Al-Dawsari's late penalty to earn Australia a memorable victory and secure the country's sixth successive appearance at a World Cup in style.
"To show that character, resilience and then quality to come back and actually take the lead and win the game, I'm delighted," said Popovic.
In Group B, Palestinian hearts were broken when they conceded a penalty deep into injury time to draw 1-1 with Oman in Amman.
Palestine, playing their home fixtures at a neutral venue, took the lead on 49 minutes when Oday Kharoub headed Adam Kaied's corner into the top corner.
Oman were reduced to 10 men in the 73rd minute after Harib Al-Saadi was shown a second yellow card.
Yet the visitors rallied to snatch a precious point in the 97th minute, Issam Al-Sabhi converting a spot-kick following a foul on Muhsen Al-Ghassani.
The result means Oman finish fourth in the group at Palestine's expense and therefore advance to the next phase of qualification.
The top two teams in each of the three groups go straight to the World Cup in the United States, Mexico and Canada, while those in third and fourth move on to the fourth round.
Taking place in October, and comprising two groups of three, there are two places at next summer's tournament up for grabs with Oman, UAE, Qatar, Iraq, Saudi Arabia and Indonesia all in the running.
- Kamada stars for Japan -
Crystal Palace forward Daichi Kamada scored twice for Japan and Paris Saint Germain's Lee Kang-in netted for South Korea as the Asian giants rounded off successful World Cup qualifying campaigns in style.
Japan romped to a 6-0 thrashing of Patrick Kluivert's Indonesia in Osaka while South Korea cruised to a 4-0 win over Kuwait in Seoul where fans were treated to a late appearance by Son Heung-min.
FA Cup winner Kamada struck twice in the first half for Japan, with Takefusa Kubo, Ryoya Morishita, Shuto Machino and substitute Mao Hosoya also on target against Indonesia, who finished fourth in Group C.
Iran and Uzbekistan are already through to next year's finals from Group A, as are Jordan and South Korea from Group B, who both secured qualification last week with a game to spare.
Jeon Jin-woo and goals from European-based trio Lee Kang-in, Oh Hyeon-gyu of Belgium's Genk and Lee Jae-sung of Germany's Mainz sealed the win.
Tottenham's Son, who has been struggling with injury, came on as a 75th-minute substitute.
Iraq confirmed third place in the group with a 1-0 victory against Jordan in Amman, the hosts having already clinched a first appearance at the World Cup.
