Chelsea manager Antonio Conte expects a searching examination when his side return to West Ham United's London Stadium on Monday, scene of one of their four defeats this season.
Only Liverpool, Arsenal and Tottenham Hotspur have bested leaders Chelsea in the Premier League, but Conte's men were knocked out of the League Cup by West Ham following a 2-1 loss in October.
Chelsea's 10-point lead is likely to have been eroded by the time they take to the field at the former Olympic Stadium and Conte says they will have to produce a much sharper display than on their last visit.
"I hope so because the result wasn't good for us and we want to try to take three points," said the Italian.
"It will be a difficult game. We all know the difficulty of derbies, but we are preparing very well for this game, in the right way with great commitment and focus.
"For sure it will be a tough game and also we will know the results of the other teams, so there will be positive or negative pressure. But we are ready to play this game and try to do better than last time."
Chelsea's defeat at West Ham occurred amid a run of 13 straight wins in the league and came after Conte made a number of changes to his starting XI.
But with in-form winger Eden Hazard expected to shrug off a knock received in training, Chelsea will be at full strength for Monday's derby.
West Ham will be without winger Michail Antonio following his dismissal in last weekend's 1-1 draw at Watford, while Angelo Ogbonna (knee) and Diafra Sakho (back) remain out.
Andy Carroll returns after two games out with a groin injury, however, and captain Mark Noble believes the towering striker could make the difference for Slaven Bilic's men.
"Andy is massive for us whenever he is fit and everyone knows it," Noble told the club website.
"He was fit for 11 (league) matches over Christmas and New Year and scored six goals, so we need to keep him available.
"Andy knows how important he is to our team and he hates not being involved with the lads on the training pitch. Having a fit Andy Carroll is a massive boost for us."
- 'Chelsea can slip' -
Carroll missed the League Cup win over Chelsea and failed to find the target when West Ham lost 2-1 at Stamford Bridge in August, but Conte remains mindful of the threat he poses.
"Andy Carroll is a really good player, very strong physically and we must pay great attention," he said. "But we must pay attention to the whole West Ham team because in the League Cup they beat us.
"We are preparing different solutions to limit the strengths of our opponent, but it's important for us to play our idea of football, bring our philosophy, try to play, score, defend very well and play with high intensity."
While Chelsea continue to carry the air of champions-elect, their momentum has slowed since their autumn surge and they have won just one of their last four away games in the league.
West Ham manager Bilic, meanwhile, believes the title race is far from over.
"It is still very open. There are many, many points available," said the Croatian.
"Like the clubs below us. Let's say we are in the position of Chelsea, or even better, regarding the clubs in the relegation zone.
"We are not afraid of our position, but you know that you need points to stay up and improve.
"Those teams who are down there, like Sunderland, Hull, they are hoping and planning to get the points. They know if they get the points they have a chance.
"It is the same with Chelsea and the five teams chasing them. They still think they have a chance to catch Chelsea if Chelsea slip, and they can slip in every game."