Keisuke Honda's first-half penalty proved the difference as defending champions Japan downed Iraq 1-0 in their Asian Cup Group D match on Friday.

Honda coolly converted from the penalty spot in the 23rd minute to give the Blue Samurai a well-deserved win in front of almost 23,000 fans at Brisbane Stadium.

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The 1-0 scoreline flattered 2007 winners Iraq, who were under immense pressure throughout and could have conceded a hatful if the Japanese had converted their many chances.

Honda was guilty of a glaring miss when he hit the post in the second half with the goal begging – the third time he hit the woodwork.

However, he managed the decisive kick of the game with his well-taken penalty, when he sent Jalal Hassan the wrong way and rolled the ball into the opposite corner.

Japan will be favourites to progress to the quarter-finals alongside Iraq in their final Group D games against Jordan and Palestine respectively.

Hamza Aldaradreh scored the first hat-trick of the Asian Cup on Friday as Jordan hammered Palestine 5-1 to keep themselves alive in the competition.

Aldaradreh finished with four goals, helping Jordan end a miserable run of 11 games without a win, but their hopes of advancing still hang in the balance with defending champions Japan to come in their final Group D game on Tuesday.

Yousef Ahmad scored with a superb curling effort after 33 minutes, before Aldaradreh doubled Jordan's advantage moments later.

The striker grabbed his second in first-half stoppage time to leave Palestine with a mountain to climb and completed his treble with a clinical strike in the 75th minute. Adrenalin pumping, he piled on the misery for Palestine with another goal from point-blank range.

But Palestine carved out a little piece of history for themselves from a pulsating match when Jaka Hbaisha smashed home a consolation goal five minutes from time.