Japan booked their place at the London Olympics with a 2-0 win over Bahrain on Wednesday, earning the country a shot at its third major title in a row.
Second-half goals from Takahiro Ogihara and Hiroshi Kiyotake were enough to put the 1968 bronze medallists through, where they join already-qualified South Korea. Uzbekistan will challenge UAE for the last automatic berth later.
Elsewhere Australia rounded off their failed campaign with a goalless home draw against Iraq, meaning Aurelio Vidmar's men played all six qualifiers - some nine hours of football - without scoring once.
South Korea, who had qualified with a game to spare as winners of Group A, stayed unbeaten heading to the London contest with a 0-0 draw against Qatar.
In Tokyo, Urawa Red Diamonds midfielder Genki Haraguchi crossed for Cerezo Osaka's Ogihara to open the scoring for Japan 10 minutes after the break.
And there was to be no way back for Bahrain, who had harboured faint hopes of reaching the play-offs, when Kiyotake netted four minutes later.
Japan's confidence will be high after their senior national team secured the Asian Cup early last year, followed by a historic World Cup title for the nation's women.
"I have a lot of players with potential. We qualified for the Olympics, but this is merely a start," said Japan's coach Takashi Sekizuka. "It was really tough to get through the Asian qualifying rounds. I feel relieved."
Uzbekistan and UAE will battle it out for Group B's first and second spot in Tashkent later with the hosts needing to win by more than one goal to snatch the automatic berth.
Iraq's draw in Gosford meant they finished ahead of Australia in third spot in group B with five points, with the hosts consigned to bottom place.
It will be the first time since 1984 that Australia will not be represented in football at the Olympics. Iraq finished fourth in Athens in 2004.
Football is played at under-23 level at the Olympics, although each team can pick up to three senior players.