Japan's Yuya Osako scored twice as the four-times champions fought back from going a goal behind to earn a 3-2 win over unfancied Turkmenistan in their Asian Cup opener on Wednesday.
Hajime Moriyasu's side, one of the favourites for the title, laboured throughout the opening 45 minutes and fell behind to a vicious long-range strike from Arslanmyrat Amanov that flew past goalkeeper Shuichi Gonda.
The Japanese rallied in the second half, however, with Osako netting two in quick succession before Ritsu Doan added a third, although a penalty from Ahmet Atayew in the 79th minute kept Turkmenistan's hopes alive until the final whistle.
Uzbekistan joined the Japanese at the top of the early Group F standings with a late 2-1 win over Oman, while Qatar scored twice in the second half to secure a 2-0 win over Lebanon in Group E.
Japan are unbeaten since Moriyasu took over from Akira Nishino in July but that record looked under threat when Amanov smashed his shot home from 25 metres as the Samurai Blue toiled in the Abu Dhabi sun.
Yet Genki Haraguchi inspired a second-half fightback, with Osako levelling the scores 11 minutes after the break when he turned to slot the ball beyond Mamed Orazmuhamedov.
Three minutes later, Werder Bremen forward Osako struck from close range after good work from Haraguchi and Yuto Nagatomo.
Doan added the third 19 minutes from fulltime only for Atayew's penalty eight minutes later to give Turkmenistan hope of snatching a draw.
"At the break I went over the first half and told my players about our transition play, the battle around the ball and the need to read the game better than we had been doing," said Moriyasu.
"We made it difficult for ourselves after conceding the goal."
Uzbekistan's Odil Ahmedov, who was named the country's Player of the Year earlier in the week, claimed their opener against Oman with a fierce free kick after 34 minutes, but Muhsen Al Ghassani levelled with 18 minutes remaining.
Eldor Shomurodov came off the bench to grab the winner five minutes from fulltime when he beat goalkeeper Faiyz Al Rashidi at his near post, although Egor Kremits' straight red card two minutes into stoppage time took some of the gloss off the win for Hector Cuper's team.
Qatar's win over Lebanon, courtesy of goals from Bassam Al Rawi and Almoez Ali, moved Felix Sanchez's side level with Saudi Arabia on three points in the Group E standings.
Al Rawi put his side ahead five minutes after the hour mark with a curling free kick while Ali put the result beyond doubt when he stabbed home from close range after goalkeeper Mehdi Khalil parried Abdelaziz Hatem's initial shot.
