Branislav Ivanovic has revealed that he and his teammates "lost control" of their minds when they began defending the Premier League title at the start of the season.
The Blues tumbled down the table in the first half of the campaign, which resulted in manager Jose Mourinho getting sacked.
Chelsea were one point above the relegation zone when Mourinho was given his marching orders in December, but since Guus Hiddink was installed as interim boss they have gone 12 games unbeaten in the top flight.
"Jose told us the hardest season in football is the year after you win because everyone else has extra motivation," Ivanovic told the Daily Mail. "We were ready for that, but we didn't start well and we lost control of our game, of our minds.
"Jose didn't change. He didn't change the way he prepared the game. He didn't change the way he treated us. He didn't change anything. He was the same."
Mourinho has been widely tipped to take over at Manchester United in the summer if current boss Louis van Gaal is sacked.