Japan were aggrieved as the officials denied Takuma Asano an equaliser after Ahmed Khalil's brace gave UAE a priceless qualifying win.
Ahmed Khalil was the hero for United Arab Emirates as they came from behind to stun hosts Japan with a 2-1 World Cup qualifying victory in Saitama.
Japan began their opening match in Group B – the final round-robin phase of AFC qualification for Russia 2018 – in confident fashion and led through Keisuke Honda's early header.
But a superb free-kick from Khalil pulled UAE level and he coolly converted a 54th minute penalty after Ryota Ohshima fouled Ismail Alhammadi.
An onslaught then followed from Vahid Halilhodzic's men and they were rightly aggrieved when the officials failed to spot substitute Takuma Asano's shot had crossed the line before being parried away by Khalid Eisa.
As well as lamenting a run of decisions going against them, Japan could also dwell on a string of missed chances in a damaging start to a competitive section also featuring Australia, Iraq, Saudi Arabia and Thailand.
Halilhodzic's side pushed their visitors back from kick-off, dominating possession before a buoyant home crowd, and they led after 11 minutes when Honda was unmarked to power home Hiroshi Kiyotake's right-wing free-kick at the back post.
Shinji Okazaki then broke clear of the UAE defence but blazed wide on the end of Shinji Kagawa's pass, before the visitors stunned Saitama Stadium with a 20th-minute leveller.
Maya Yoshida was booked after Ali Mabkhout went to ground theatrically under his challenge but there was nothing dubious about Khalil's resulting strike, a sumptuous effort that Shusaku Nishikawa could only palm against the underside of his crossbar on its way in.
UAE did not heed the warning over Honda's aerial prowess and the AC Milan midfielder was again left unattended on the end of a floated cross from Gotoku Sakai.
Eisa shovelled the ball off his goalline and Kagawa should have done better than prodding the rebound wide.
Japan remained in control until the interval but were almost behind against the run of play when Mabkhout raced clear to be denied by Nishikawa.
Ohshima had a stinging drive turned over after half-time but it was his trip on Alhammadi at the end of an untidy passage of play that allowed captain Khalil to nonchalantly chip home from 12 yards.
Kiyotake failed to connect with a low cross as Japan sought an equaliser and Okazaki headed a Honda delivery against the bar before Asano being wrongfully denied added controversy to a frantic finale.