The Thais ensured they finished their Group C campaign with three wins from three by beating South East Asia rivals Vietnam 5-2 on Tuesday.

The War Elephants are regarded as one of Asia’s strongest futsal sides but have yet to secure an AFC Futsal Championship title in 10 attempts.

Their best performance came in 2008 when they stormed to the final with five successive victories but lost 4-0 to nine-time champions Iran.

And Mandez fears they could fall just short once again unless they stop making unforced errors during matches.

“We had a very bad game (against Vietnam) and I am ashamed about that,” he said.

“We need to seriously think about that before the next match and make sure we do not repeat the mistakes that we made.”

Mandez’s counterpart Guilherme Da Silveira also believes his side need to improve if they are to have a chance of beating Thailand

China finished second in Group D with two wins and one defeat but almost missed out on a place in the last eight as they allowed Iraq to stage a late fight-back in their final group game on Tuesday.

China were leading 7-2 with six minutes remaining but took their foot off the pedal and Iraq took full advantage with four goals in five minutes to set-up a tense finish.

However, China did enough to hold out for the final whistle and secure a 7-6 win, but Da Silveira warned his players they may not be so lucky again.

“My players were too relaxed once they had built a big lead. I already told them in the changing rooms that this does not happen again," he said.

“Now, I hope, we will win against Thailand.”