West Ham manager Alan Pardew believes the dismissal of Chelsea midfielder Maniche affected his side more than the reigning champions.
West Ham had stunned the Barclays Premiership leaders with an 11th minute goal from James Collins and then got a further boost five minutes later when Maniche was dismissed for a reckless challenge on Lionel Scaloni.
But despite being in a commanding position, West Ham allowed Chelsea to produce one of the most exhilarating comebacks of the season to win 4-1.
Two goals in three first-half minutes from Didier Drogba put Chelsea in control and further strikes from captain John Terry and William Gallas left Pardew deflated.
Pardew said: 'We looked okay at the start and got a good goal from set-play.
'But the incident where Maniche got sent off seemed to inspire them.
'We thought we were doing enough but you have to say the 10 players Chelsea had produced a few world class performances and we had problems with them today.
'We were unhappy with the goals - the first one was especially disappointing and it gave them a foothold back in the game.
'I looked at the team and felt we had lost a little of the exuberance and positivity we've been about all year. You can't afford to do that on a big stage.
'We were always playing within ourselves and it was a bit of an issue.
'We talked about it at half-time but the third goal was a disappointing one and it knocked us back again.
'Our exuberance was knocked out of us at some point in the game.'
Pardew and his side had spent the week leading up to the game in Dubai but the manager admitted the mini-break had been a mistake.
He said: 'This game got way from us today and we'll have to look at that trip to Dubai because we obviously didn't get it right.
'It was a very disappointing day. We took the trip to Dubai thinking we would come back fresh and be ready for this game.
'But in fact it did not work out that way for us. Bolton made the same trip and got a great result at Arsenal, but it hasn't worked for us.
'We knew Chelsea were gearing up for this game. They'd had some criticism at their door and they were going to make a response. We needed to be ready for that but after getting a great start, we didn't react.
'The sending off affected us more than them. I didn't see it particularly clearly but the referee made the decision pretty quickly, so he must have had a good view of it.'
Pardew also admitted they had a problem with Didier Drogba, who was outstanding for Chelsea - making two goals and scoring one himself.
The Hammers boss conceded: 'We had a problem with Drogba in the first game and we had a problem again with him today.
'None of their players put in a world class performance like Drogba did, he was a real problem.
West Ham's season is very much dependent on the FA Cup where they face Charlton or Middlesbrough in the semi-final and Pardew admitted they could be accused of thinking too much about that after their performance at Stamford Bridge.
He added: 'When you put in a performance like we did today you can put the accusation at our door that we are looking at the cup.
'On today's evidence that accusation stands up and in some ways we've let the fans down.'