Japan needed an injury-time goal to spare their blushes in a 1-1 draw with Jordan in their opening game, but they have since gone from strength to strength and booked their last-eight place by thrashing Saudi Arabia 5-0.
Italian coach Alberto Zaccheroni has the team playing a pleasing brand of attacking football and Metsu believes Japan have improved significantly since they reached the last 16 at last year's FIFA World Cup™ in South Africa.
"They play fantastic football. I like their style of play," said Frenchman Metsu, who is bidding to guide Qatar to the last four at the continental showdown for the first time in their history. "They didn't win their first game, but they've kept the ball really well in all three of their games so far and I think they're a better team than they were at the World Cup.
"Looking at their match against Saudi Arabia, you could call them the Barcelona of Asia. We can't compare what happened against the Saudis to our match though, as they [Saudi Arabia] had already been eliminated. But Japan are one of the best teams in Asia. They're well organised and disciplined. Sometimes you feel like you'd need a computer to beat Japan."
Qatar have also gained momentum since losing their first game to Uzbekistan, having beaten China PR 2-0 and then out-classed Kuwait 3-0 to reach the last eight. Tomorrow's game takes place at the stadium where Metsu spent "two good years" in charge of Qatari club side Al Gharafa.
He called on the Qatari fans, who deserted in droves towards the end of the loss to Uzbekistan, to play their role in the team's bid to reach the semi-finals. "We need the fans and the supporters if we want to have a good result," he said. "It's important they support us from the first to the last minute."
Zaccheroni acknowledged the impact that the supporters could have on the match, but said his players were not overwhelmed by the prospect of trying to eliminate the host nation.
"They know that one team is home, one is away," said the former AC Milan coach. "International players are used to this atmosphere and have no problem. I'll tell the young players to be careful as they don't have the same experience. On the pitch it's always 11 versus 11. If we play our own game, we should be OK."
Japan's demolition of Saudi Arabia came despite the absence through injury of star playmaker Keisuke Honda, but he is expected to be fit to face Qatar. The nature of Japan's victory against fellow three-time champions the Saudis has raised expectations that they can win the tournament, but Zaccheroni said the match with Qatar was a completely different prospect.
"We took our chances in the match [against Saudi Arabia] and at the same time, our opponents attacked us, so they left space for us," he explained. "Secondly, we sped up our performance, and the content of our performances is getting better and better.