Four-time champions Japan eased into the quarter-finals of the Asian Cup with a clinical 3-1 victory over Bahrain here on Wednesday with goals from Ritsu Doan, Takefusa Kubo and Ayase Ueda.

Bahrain coach Juan Anotnio Pizzi had been looking to heal old wounds after his Saudi Arabia team lost to Japan at the same stage in 2019 but Hajime Moriyasu's side put in a commanding performance and rarely looked troubled against the Gulf nation.

"All Asian teams here at the Asian Cup are getting better, the level of football has grown.

"But even though other teams are growing, we've managed to improve as well which is down to our players' efforts," Moriyasu told reporters.

"But I don't think today's performances were 100 per cent and we can still improve."

Japan took the lead in the 31st minute when Seiya Maikuma unleashed a venomous strike that crashed off the post but midfielder Doan was alert to pounce on the rebound to score from close range.

The game also saw Kaoru Mitoma make his return from injury and the Brighton & Hove Albion winger sent a buzz around the arena when he made several chances with his agility and speed on the ball, skipping past defenders with sublime ease.

But Japan did not capitalise on his forays into the box.