Vietnam booked their place in the last eight as runners-up from Group D after notching up an impressive 1-0 win over Australia, but it was Iraq's showing as they claimed top spot in Group C that has the coach from Korea Republic in a cautious frame of mind.

"I saw Iraq’s matches against Saudi Arabia, Jordan and Malaysia, and they changed their style in each match,” he said.

“They clearly were very strong, and they have very talented players who can adapt to any change in tactics.

Iraq opened their campaign with a 4-1 victory over Malaysia before being held scoreless in a draw with Saudi Arabia.

But Resan scored the only goal of the game on Tuesday as Iraq defeated Jordan to secure top spot in Group C and set up a quarter-final meeting with the yet-to-be-determined runners-up in Group D.

"We thank God that we qualified for the quarter-finals, and that we also performed well in all of our matches, maybe with the exception of the match against Saudi Arabia,” he said.

“In that game as our tactics were different, but we got back on track against Jordan. We matched our expectations, and we hope we can continue to be successful in the coming rounds."

The meeting with Saudi Arabia saw both teams engage in a damage limitation exercise that yielded little in the way of goal-mouth action as Iraq, in particular, set aside their attacking instincts to ensure they picked up at least a point.

Xuan Truong  and his compatriots secured a 0-0 draw with Syria on Wednesday to seal their place in the last eight of the competition, where they will meet Iraq on Saturday, having previously defeated Australia and narrowly lost to Korea Republic.

"As you could see in the matches against Australia, Korea and Syria, they were all very strong, and with our ability alone we can't defeat them, so we had to use our fighting spirit, and that was a good way to win against them,” he said.

Vietnam’s ability to keep opposing teams at bay has been a factor in their progress from Group D as runners-up behind the Koreans, but the 22-year-old Korea-based midfielder stressed that coach Park Hang-seo’s influence was key to the team’s success so far.

"I don't totally agree that our defence was very good in the matches we played so far, because as you can see there was a lot of mistakes today, and in the last two games also, so our defence is not perfect yet, and we should try more,” he said.