The only goal was scored by midfielder Ito Junya in the first half.
The NHK public broadcaster said the team faced difficult challenges while Tokyo-Sports news site analysed problems of the Japanese team. It pointed out the lack of deciding power and the two midfielders of Asano and Furuhashi came to the field from the middle of the second half, but they could not get any additional points.
Yahoo!Japan commented that the team in blue has problems in scoring as Ito might be the one who gave the most troubles to Vietnam.
Asahi Shimbun also said that Japan encountered difficulties in teamwork as many key players had only one day to prepare for the game.
As it is the fifth consecutive defeat of Vietnam, they have yet to collect any points and stand at the bottom of Group B.
Vietnam are to host group leaders Saudi Arabia while Japan will fly to Muscat to play Oman. Both games will take place on November 16.
This is the first time that Vietnam has played in the final qualifying round. They are in the same group with Japan, Australia, Saudi Arabia, China and Oman.