David Luiz has attributed Chelsea's inconsistency under Maurizio Sarri to the players having difficulty coming to terms with not challenging for the title.
Chelsea won the 2016-17 Premier League title in Antonio Conte's first season in charge, but finished fifth last term, 30 points adrift of Manchester City, who beat them in Sunday's Carabao Cup final on penalties.
The Blues are sixth ahead of the midweek Premier League fixtures, which see them face third-placed Tottenham on Wednesday night in a match which is crucial to their bid to return to the Champions League and to the future of Sarri, just seven months into his reign as head coach.
Luiz said: "Chelsea is a team which should be fighting for the Premier League and now we are seeing it is a bit far, so it is not the same mentality. It is up to us to pass this step."
Spurs inflicted Sarri's first competitive loss, after an 18-game unbeaten start, on November 24, but Chelsea exacted revenge in the two-legged League Cup semi-finals, winning on penalties.
Since, Chelsea have lost 4-0 at Bournemouth and 6-0 at City – their heaviest defeat in 28 years – while fans voiced their disapproval of Sarri's methods in the FA Cup exit to Manchester United.
The performance at Wembley, stifling City and creating chances to win the match, with Eden Hazard and N'Golo Kante excelling, will likely have bought Sarri some time, even if the positives were then overshadowed by goalkeeper Kepa Arrizabalaga's refusal to be substituted.
Avoid embarrassment against Tottenham and it appears likely Sarri will limp on, possibly to the end of the season, with favourable fixtures coming in March.
"They are playing together for many years, so it will be tough game," Luiz said of Mauricio Pochettino's Spurs.
"I also love the way Pochettino sets up his team, he brings through an amazing generation, especially with English players like Dele Alli, (Harry) Kane, (Eric) Dier."
Luiz's own future is uncertain, given he is 32 in April and out of contract at the end of the season.
The Brazil defender fell out of favour under Conte, partly due to a knee injury, but has been integral for Sarri.
Sarri has already urged Chelsea to bend their usual policy of offering only 12-month extensions to those over 30 to retain Luiz, who says he is thriving.
"It's one of the best seasons I've had individually, but, for me, this doesn't count because I want my team to win," Luiz said.
"It's better that my team wins 5-4 and it's better that everyone talks bad about me but my team is winning than I'm doing a great job and we're still not winning."
