Co-hosts Vietnam were heading for a place in the quarter-finals of the competition for the first time in their history until Sebastian Quintana headed home from close range with 11 minutes remaining to earn a draw for Qatar - for the second successive game, following his 88th-minute heroics against Japan.

Vietnam were handed a 32nd-minute gift when Qatar goalkeeper Mohamed Saqr allowed Phan Thanh Binh's seemingly harmless first-half strike to squirm under his body and agonisingly roll over the line.

"We did not push forward fully to score the second goal but if you get a little luck you might get a chance and we had a chance with (Le) Cong Vinh on the left but he hit the ball over the bar," said Riedl.

"We always tried to have eight players behind the ball at all times when we were in the lead.

"Qatar are very strong in attack and were superior in the air and because we lack in the height department it is difficult, especially in the last 20 minutes when they risked everything to score.

"I think we got a lucky result today, but sometimes people who are fighting hard get a good result in football. Qatar, especially in the last 20 to 25 minutes, were clearly the better team.

"They created a lot of chances and hit the crossbar and also struck the post as we faced some difficult situations in our area, so I am very happy with the result."

Vietnam were seen as underdogs before the tournament but know a point against defending champions Japan on Monday would give them a chance of making the last eight.

Their chances have not been helped, however, by Binh Doung defender Vu Nhu Thanh being carried off in the 55th minute, while goalkeeper Duong Hong Son required treatment on several occasions following a first-half collision.

Qatar coach Dzemaludin Musovic has backed goalkeeper Saqr to bounce back from his costly error, insisting the Al Sadd custodian is one of the best in Asia.

"It's part of football," he said. "This may happen once in 10 or 20 games. But he is the best we have and he will continue, no problem. Playing in a position like his, it's possible to make a mistake like this.

"We dominated for the first 30 minutes and should have scored a goal. But the situation changed when Vietnam scored the goal."

Qatar face the United Arab Emirates in their final Group B game on Monday in Ho Chi Minh City, knowing they must win to stay in contention for a place in the last eight.

"Qualification for the second round is still wide open," added Musovic. "Tomorrow's game between Japan and the Emirates is very important. Because it is a close competition, who will qualify for the next round will be decided in the last game."