Enzo Maresca has blamed Chelsea's post-match celebrations against Nottingham Forest for their slow start in the UEFA Conference League final against Real Betis.
The Blues completed a historic set of European trophies after beating their Spanish counterparts 4-1 on Wednesday night - having fought back from one-goal down.
Though Chelsea were electric in the second-half, their performance before the break was lacklustre and resulted in full-back Malo Gusto being substituted at half-time.
After the match, Maresca discussed Chelsea's slow start and attributed it to their celebrations after beating Forest and qualifying for the Champions League.
Speaking to TNT Sports, Maresca said: 'I think we approached the game in the wrong way. I expected it a bit because the happiness was too much after Nottingham.
'So we struggled a bit to start but in the second-half we were much better'.
Pressed further on the issues his side faced, he explained: 'The happiness and a little bit of tiredness. We had 48 hours less than them.
'They played Friday for nothing. We played on Sunday for a big target. But in the second half we were much better'.
The Blues boss was then quizzed on the decision to take off Gusto - and replace him with club captain Reece James - at the interval.
Maresca said: 'Malo is one of my favourite players. The problem is, the first goal that we conceded was because he missed the pass.
'But they are young and they don't understand that if you make a mistake, you have to continue. For me, he is a top player'.
It was Betis who opened the scoring, in the ninth minute of the match, after a well-taken strike by Abdessamad Ezzalzouli flew beyond Filip Jorgensen.
Enzo Maresca's Blues battled away for a response in the remainder of the first-half - however were left frustrated as they failed to find an answer.
Malo Gusto was singled out as one of Chelsea's struggling stars and was replaced by club captain Reece James in a bid to claw themselves back into the game.
Though it took longer than they would've liked, they did exactly that in the 65th minute after Enzo Fernandez nodded home from a floated Cole Palmer cross.
The momentum swung in Chelsea's favour and just six minutes later they were ahead as Palmer once again crafted a goal out of nothing and gifted a six-yard header for Nicolas Jackson to finish.
Jadon Sancho added a third with a curling effort before Moises Caicedo rounded off the scoring in added time.