Yuya Osako netted a quickfire double as former champions Japan survived a scare to beat Turkmenistan 3-2 in their opening game on Wednesday.
The Blue Samurai reached the last 16 at last year's World Cup but had to fight back from a goal down at halftime in an absorbing Group F clash.
Turkmenistan captain Arslan Amanov put the plucky underdogs ahead after 26 minutes, unleashing a ferocious long-range drive that arrowed into the top corner.
But Osako produced a smart turn and finish inside the box to equalise for Japan 10 minutes into the second half following sustained pressure from the four-time Asian champions.
The Werder Bremen striker put Japan in front four minutes later, tapping into an empty net after Yuto Nagatomo's dinked pass over goalkeeper Mammet Orazmuhammedow.
Ritsu Doan added a deflected third after 70 minutes as Turkmenistan began to wilt.
But Ahmet Atayev swept home a penalty 11 minutes from time to ensure a nervous finish for Japan, who are now unbeaten in six matches since Hajime Moriyasu took charge after the World Cup.
The Japanese are seeking to make up for their Asian Cup flop four years ago when they lost on penalties to UAE in the quarter-finals.