Vietnam's under-23s were stunned by Turkmenistan 6-2 in their second match in the Asian Games on Nov. 10.
The loss saw Vietnam, who beat Bahrain 3-1 on Nov. 8, plunge to third place in Group B.
Turkmenistan, who lost 4-1 to Iran, stand second; ahead of Vietnam with a better goal difference.
Vietnam would have qualified for the last 16 if they had beaten Turkmenistan in the match at Guangdong People's Stadium on Nov. 10. But the Vietnamese team defence collapsed in their worst performance in recent years, while the strikers missed a dozen clear-cut chances to score before half time.
The central Asian team took a first half 2-0 lead after Serda and Aleksandra waltzed through the Vietnamese back four.
Vietnam's Pham Thanh Luong, Ngoc Dieu and Anh Duc all failed to make their close-range chances count.
Turkmenistan nullified Vietnam's U-23s by bypassing midfield with a judicious use of the long ball, and stoutly defended their lead through to half time.
Five minutes into the second half, Belyh Maksim headed home the third goal for the central Asian team from a corner kick before Arslanmyrat broke down the left flank to net the ball on the 60th minute mark.
Arslanmyrat and his team-mate Aleksandr Bolyan both unmarked, scored on the 72nd and 82nd minute.
Trong Hoang pulled back a goal for Vietnam on the 85th minute, before Anh Duc netted the ball with a close finish.
Duc also missed five goal scoring chances in the second half.
Iran played Bahrain in a late match on Nov. 10.
Vietnam must win defeat powerhouses Iran in their last match on Nov. 13 if they want to qualify for the knock-out round.
