Uzbekistan rallied to beat Qatar 5-1 in Tashkent on Tuesday but came up two goals short of securing their first appearance in a World Cup after Iran's win in South Korea sent both those teams to Brazil.
Uzbekistan were pushed into third place in Asian qualifying Group A, behind Iran and South Korea, and will have to rely on the playoff route to make it to next year's showpiece event.
Iran beat South Korea 1-0 in Ulsan to top their qualifying group, and South Korea also qualified automatically for the finals after finishing above Uzbekistan on goal difference.
If Uzbekistan had beaten Qatar by a margin of six goals they would have overhauled South Korea as runners-up, but their scoring spree began too late for them to make serious inroads.
The third-place finishers in both Asian qualifying groups will meet in a two-leg playoff, with the winners taking on a South American side in another two-leg playoff for the right to play in Brazil next year.
The hosts missed a flurry of chances in the first half and paid for their profligacy when Qatar took the lead in the 37th minute through Abdulqadir Ilyas's first international goal.
Bahodir Nasimov found the Uzbeks' equaliser in the 60th minute with his first touch after replacing Alexander Geynrikh.
Oleg Zoteev, another substitute, put Uzbekistan in the lead before Nasimov added his second. Odil Ahmedov scored in the 87th minute and Ulugbek Bakaev added the fifth in injury time.
Celebrations, though, were shortlived for both the home crowd and the players as news of Iran's victory reached the Bunyodkor Stadium.
"It is very unfortunate for us as we wanted to qualify for the World Cup and celebrate with our fans. It is a shame that we could not achieve our aim," Uzbekistan coach Mirdjalal Kasimov told reporters.
"We couldn't score in the first half as the Qatar goalkeeper played very well. We made changes in the second half and that's why we scored five goals, but Iran beat Korea.
"We will continue to battle in the next round, although we need a little time to recover. Life goes on and we will give our best to qualify for Brazil."
Qatar's debutant goalkeeper, Ahmed Abonora, made several saves in the first half to frustrate Uzbekistan in their quest to improve their goal difference.
Abonora twice denied Geynrikh from close range and pulled off an acrobatic save to keep out Uzbekistan captain Server Djeparov's volley from outside the box.
Uzbekistan will face either Oman or Jordan in the Asia playoff, depending on the result of Tuesday's final Group B qualifier between the two sides in Amman.
(Reporting by Sudipto Ganguly in Mumbai, editing by Stephen Wood)