Eden Hazard warned Chelsea against complacency, stating "anything can happen" and urging them to stay focused in their Premier League title bid.
Antonio Conte's men are five points clear at the top of the table, but were beaten by Tottenham last time out in the league.
Hazard said they still had work to do as they prepare for a trip to Leicester City on Saturday.
"We know this league is difficult – you never know – anything can happen," the Belgium international told talkSPORT.
"Now, we are top of the league, but the other teams are very strong and they want to close the gap and comeback quickly.
"We have to be ready for everything, we are in this position and we know what to do."
Hazard helped Chelsea to the league title in 2014-15 before they finished 10th last season.
The 26-year-old said he felt for Leicester, last season's champions who are just six points clear of the relegation zone.
"It's difficult. Like Chelsea last season – we won the title – but the year after is always difficult because the opponent want to beat the champion," Hazard said.
"They have to deal with it and they play Champions League so [they need] more energy, they lost one important player like N'Golo [Kante to Chelsea].
"We are in full confidence. We lost against Tottenham in the last game, but we are top of the league and we also want to stay top of the league."