Genki Haraguchi smashed home a controversial penalty as former champions Japan scraped a 1-0 win over Oman to book their place in the last 16 of the Asian Cup on Sunday.

Japan, who have scooped Asian football's biggest prize on four occasions, enjoyed their share of good fortune against Oman in Abu Dhabi.

Haraguchi clipped the crossbar after just two minutes before Takumi Minamino fluffed a handful of golden opportunities.

That profligacy almost came back to haunt the Blue Samurai as Oman flooded forward and Muhsen Al-Ghassani shaved the post from an acute angle.

But Haraguchi settled Japan's nerves in the 28th minute, converting from the spot after he had appeared to go down easily under minimal contact from Oman captain Ahmed Al-Mahaijri.

Oman had extra reason to feel aggrieved when their own penalty claims were waved away just before half-time after Yuto Nagatomo looked to have handled a Salaah Al-Yahyaei drive.

Japan reached the knockout stages of last year's World Cup but they squeaked past Turkmenistan 3-2 in their opening Group F game and were poor against Oman, who almost equalised when Raed Saleh's acrobatic late volley flashed wide.

But the Japanese remain unbeaten in seven matches since Hajime Moriyasu took charge after the World Cup and have now lost just one of their last 30 games at the Asian Cup, excluding penalty shootouts.

Japan are seeking to make up for their Asian Cup flop four years ago when they lost on penalties to the United Arab Emirates in the quarter-finals.

But they will need to find another gear if they are to threaten Iran, who are purring, and a South Korea side boosted by the arrival of Tottenham forward Son Heung-min.

Japan will take on either Saudi Arabia or Qatar after qualifying for the knockout stage for the eighth consecutive time.

In the day's late kickoff, Eldor Shomurodov bagged a first-half brace as Uzbekistan crushed Turkmenistan 4-0 in a clash of former Soviet republics to progress and go top of Group F ahead of Japan on goal difference.