Chelsea manager Roberto Di Matteo bemoaned a "sloppy start" after his side were humiliated by Atletico Madrid in the UEFA Super Cup.
Striker Radamel Falcao showed just why the Blues had been interested in signing him with a first-half hat-trick that helped the Spanish side cruise to an emphatic 4-1 victory in Monaco.
The Colombian put last year's Europa League winners 2-0 up with goals after six and 19 minutes before completing his treble just before the break.
Joao Miranda added a fourth on the hour mark for Atletico before defender Gary Cahill rounded out the scoring with a late consolation effort for Chelsea.
"The first half we started very sloppy," Di Matteo said.
"It was a slow start and if you give Falcao space he's very dangerous and we should have blocked him before that.
"We didn't have much penetration. It went in their favour with the early goal and we found it difficult to find the space in the middle and tried to go our wide.
"We were very defensive and they countered on us."
Cahill claimed the English club, who had gone into the match off the back of three Premier League wins at the start of the new domestic campaign, "fell to pieces".
Falcao was certainly a handful for the Blues throughout - only the woodwork denied him from scoring two more goals in an outstanding personal display.
"We played below par. Today we fell to pieces," Cahill told Sky Sports.
"We started the game sloppy and that went right through the game. If we're honest with ourselves everyone was below par today and it was embarrassing at times.
"We approach every game in the same way. It was a massive game tonight and we let ourselves down and passed up a great opportunity.
"It is difficult. Obviously we will look to bounce back in the league as today was unacceptable."