Hussein struck twice in the first half at Education City Stadium, with a 93rd-minute header from Wataru Endo proving to be too little, too late for Japan.

The famous win lifts Iraq, the 2007 champion, to the top of Group D with six points from two games and guarantees it a spot in the Round of 16. 

Four-time winner Japan, Asia's highest-ranked team at No.17, is second with three points.

Iraq took the lead after just six minutes when Japan goalkeeper Zion Suzuki palmed Ali Jasim's cross from the left straight to Hussein, who headed it home.

Japan streamed forward in search of an equaliser but Iraq defended in numbers before doubling its lead in first-half stoppage-time as Hussein headed in Aymed Yahya's cross. The goal was given after a VAR review to check if the ball had rolled out of play in the build-up.

It looked like Japan had been awarded a penalty 10 minutes into the second half as Takuma Asano was judged to have been fouled by Rebin Sulaka. However, referee Khalid Al-Turais overturned his original decision after viewing the pitchside monitor.

Liverpool midfielder Endo eventually got Japan within a goal in added time after goalkeeper Jalal Hachim failed to collect the ball but it was not enough to prevent his country's first group-stage loss at the Asian Cup since 1988.

Vietnam lost 1-0 to Indonesia in the other Group D game, before Iran beat Hong Kong by the same scoreline in Group C.