Dinamo Zagreb claimed a shock victory over Chelsea in their Champions League group stage opener on Tuesday as they beat the 2021 European champions 1-0 at home thanks to a blistering solo run from Croatian forward Mislav Orsic.
Zagreb had conceded in every league game this season but Ante Cacic's team kept a clean sheet against the Premier League side, who topped Europe's transfer spending charts with an outlay of over 250 million pounds this summer.
Chelsea have now lost three of their last five matches in all competitions and Thomas Tuchel was seen fuming on the touchlineas his 100th matchin charge of the London club ended in defeat.
Zagreb opened the scoring against the run of play when Orsic was sent through on goal on a solo counter-attack, outrunning Chelsea's new recruit Wesley Fofana and beating goalkeeper Kepa Arrizabalaga with a delicate touch.
"It's an underperformance from us. We don't finish our half-chances. We conceded a counter-attack that is far too easy," Tuchel told BT Sport.
"There's too much to analyse, I am part of this. We are clearly not there, where we need to be and where we can be."
Chelsea had created scoring opportunities in the opening stages but were deflated by the goal and Tuchel's side looked short of ideas in front of a resolute Zagreb defence.
Pierre-Emerick Aubameyang made his debut alongside Raheem Sterling and Kai Havertz in the front line but they failed to click while Arrizabalaga was called into action twice to deny Zagreb, the second an acrobatic save to parry a shot from distance.
Chelsea did not threaten in the box until Tuchel made all five substitutions but Zagreb held firm. Goalkeeper Dominik Livakovic also made a crucial reflex save from a stinging Mason Mount shot late in the game.
"At the moment, everything is missing. I will not talk about individuals, we play as a team, we lose as a team," Tuchel added.
"I need to find a solution for the next match. It's not enough."