Chelsea boss Antonio Conte has blamed his team's ouster in the fourth-round of the English Football League Cup by West Ham on the early goal they conceded in the second half on Wednesday night.
Cheihkou Kouyate opened the scoring for West Ham with a superb header in the first half.
And just two minutes into the second half, Edimilson Fernandez doubled West Ham's lead.
Gary Cahill reduced the deficit deep into stoppage time, but West Ham held on to advance into the quarter-finals.
In his post-match analysis of the game, Conte hailed the performance of his players despite the defeat, and added the goal by Fernandez ruined Chelsea's plans.
"We knew these types of game are very difficult, but I think we played with good intensity and created many chances," Conte remarked.
"We didn't expect the second goal so early. This changed our plan and then we tried to change the situation with substitutions.
"I saw good spirit in my players. They tried until the end to change the result and created many chances but scored only at the end of the match. Today we were a bit unlucky in this aspect," Conte said.
The former Juventus boss said Chelsea will put the defeat behind them and focus on their league game against Southampton on Sunday.
"Usually you learn more after a defeat than a win. I am optimistic because I saw the right spirit, it's very important.
"Tomorrow we start to work for the game on Sunday. We know we play a very tough game against Southampton, who are in a good moment."