Frank Lampard suffered his first defeat as Chelsea boss as Kawasaki Frontale scored late to snatch victory in Yokohama.
Leandro Damiao headed in at the back post as the hosts took advantage of a rare opportunity, pouncing on a defensive mistake from David Luiz to seal an unlikely pre-season win.
On an otherwise disappointing afternoon for Chelsea, Christian Pulisic made his debut as a second-half substitute.
Granted an extended summer break following the Copa America, Pulisic was named among the substitutes after joining the tour late and was thrown on in place of Mason Mount in the second half.
That was the highlight in an otherwise uninspiring performance from Chelsea, who were lifted by the introduction of Ross Barkley at the interval but still failed to find the breakthrough at the Nissan Stadium.