Iraq coach Jesus Casas said his team were "close to perfect" in stunning Asian Cup favorites Japan 2-1 on Friday to reach the knockout rounds.
Aymen Hussein scored two first-half headers in front of nearly 40,000 in Doha to consign four-time champions Japan to a first Asian Cup group-stage defeat in 26 matches.
It also set Japan on a potential collision course with South Korea in the last 16, assuming they still progress.
Casas said that the first big shock of the tournament was "only one win" but hailed it as "a great day for Iraqi people".
"I think the perfect match doesn't exist," said the Spaniard.
"It's impossible to have a perfect match, but we were close to perfect."
Hussein headed Iraq -- ranked 63 in the world to Japan's 17 -- into the lead in the fifth minute and struck again in first-half injury time.
Iraq endured a nervous finish after Liverpool's Wataru Endo pulled one back in the third of eight minutes of injury time at the end of the game.
But they held on and now have six points after beating Indonesia 3-1 in their opening match.
They play Vietnam in their final pool-stage game on Wednesday and will be looking to top Group D.
"All the players were concentrating on this match and we were all ready for it," said Hussein, who also scored against Indonesia.
"We did everything the coach wanted -- we worked very hard during the week and we played a great game because we were really concentrated on our work."
'Football is fighting'
Japan have three points after beating Vietnam 4-2 in their opener and face Indonesia, also on Wednesday.
Hajime Moriyasu's side went into the game on the back of a 10-game winning streak in which they scored 43 goals.
They beat Spain and Germany to reach the last 16 of the 2022 Qatar World Cup.
But Japan had no answer to the power and aggression of an Iraq side roared on by most of the crowd at Education City Stadium.
"Football is fighting. You need to be competitive -- if not, it is impossible to win a match," said Casas.
"I choose the players that can be fighters, but good players too.
"The difference at this level with the national team is you need balance between fighting and quality."
Hussein headed home for the opening goal when the ball fell to him after Japan goalkeeper Zion Suzuki flapped at a cross.
He notched his second just before the half-time whistle, holding off Hiroki Ito to nod home from close range.
Japan won a penalty in the 56th minute when Rebin Solaka was adjudged to have tripped Takuma Asano, but it was overturned when a VAR check showed the tackle to have been a clean one.
Endo gave Japan hope when he pulled a goal back deep in injury time, but Iraq held on.
"The atmosphere was like an away game and conceding early hurt us," said Moriyasu.
"Conceding at the end of the first half hit us hard and made it a very difficult game. We need to learn from our mistakes."
Iraq upset the odds to win the Asian Cup in 2007.
Casas would not be drawn on his team's chances of lifting the trophy again and refused to look past the next game.
"Now it is Vietnam, and after we will see," he said.
