Antonio Conte has claimed that Chelsea's players were "tired" as the Blues fell to a shock 1-0 defeat at West Ham United on Saturday.
Chelsea, who were in Champions League action against Atletico Madrid in midweek, conceded after just six minutes at the London Stadium through Marko Arnautovic.
The Blues were unable to break down the opposition and the final whistle saw them remain 11 points behind Manchester City, who have a game in hand.
"Our start was bad but today we played a bit tired. To face one game every two games always with the same players is very difficult. And we have just started this period," Conte told reporters after the match.
"You have to move the ball quickly. But I repeat, we saw today a bit of tiredness in my players, especially in the last pass, we did a lot of mistakes. We must be disappointed.
"I repeat, we create many chances but were not able to score. We have to go and to play game by game, to be focused. Don't forget in this league it is very difficult. There are six top teams and four go to Champions League. We have to fight and do our best."
Chelsea return to action on Tuesday night when they play Huddersfield Town away in the Premier League.
