Kurt Zouma has suggested it is taking Chelsea time to adjust to being the defending Barclays Premier League champions.
Jose Mourinho's side are the one the others are trying to dethrone and on Saturday lost 2-1 to Crystal Palace - the team against whom they secured the title in May.
Chelsea, after a second loss in Mourinho's 100th home league game, have four points from their opening four matches and are eight points behind rivals Manchester City.
"We have to improve everything," Zouma told Chelsea TV. "Mentally we have to improve. The season after we are champions, it's really difficult to prepare ourselves.
"To improve is more difficult, but we have to improve ourselves and keep going, keep working."
Zouma believes the international break comes at a good time for Chelsea, who next face Everton on September 12.
They could yet add Toffees defender John Stones to their ranks, but the Merseyside club have so far resisted offers.
"We have to think about winning points and after the break will be good for us, I think," the France defender said.
Mourinho felt Chelsea should have had a penalty when the score was 0-0, when Zouma had his shirt pulled by Connor Wickham.
Zouma added: "I think it was a penalty kick. The referee didn't whistle, but the game wasn't over with that."
