Head coach Thomas Tuchel has acknowledged that his Chelsea side have looked "tired mentally" during their recent games.
Chelsea have already amassed 59 matches in all competitions this season, with 10 of those fixtures being played since the March international break.
Tuchel was left frustrated as Chelsea let slip a two-goal lead against Wolverhampton Wanderers on Saturday, their opponents netting their equaliser in the seventh minute of added-on time.
Ahead of Chelsea's fixture at Leeds United on Wednesday evening, the Blues boss has admitted that there have been signs that Chelsea's energy levels and concentration have started to wane.
Speaking to reporters at a press conference, Tuchel said: "We look a bit drained, we look tired mentally when I look at our games on the sidelines. This is understandable given the circumstances around the club in which we play, it is draining, it is challenging.
"Then we had some big knockout games to play after the international break with huge emotional input and emotions to also deal with, then suddenly be in the race with matches against four teams in Premier League. It is quite challenging, and we have a lot of matches in our legs and in our bones, and we feel it.
"We need to reach a certain level that is possible and I think we can do better than we did in the last two matches. The positive thing is that I feel the will, feel the motivation. The motivation was very high to turn things around against Wolverhampton, it was almost too high in some situations."
The upcoming game at Elland Road comes three days before Chelsea are due to face Liverpool in the FA Cup final.
