Tottenham possess a five-point advantage over their hosts but have just been demoted to fourth place in the Premier League table by Arsenal, who were 10 points adrift of their local rivals just a few weeks ago.
Chelsea, in fifth, are the only English club still in this season's Champions League but will travel to Portugal to face Benfica in the quarter-finals on Tuesday having won just two domestic league fixtures since January 14.
Tottenham are in a similarly poor run of form, having taken just nine points from a possible 27 since being within touching distance of then-leaders Manchester City on January 11.
But they also know an away win on a ground where Tottenham have not tasted victory since 1990 would put Chelsea at a severe disadvantage in the chase for the final Champions League qualification place.
Chelsea lost 2-1 at Manchester City on Wednesday despite having taken the lead but Gary Cahill, the Blues' goal-scorer, was confident of derby success.
"Arsenal are having decent form and Spurs have been hit the last few games," Cahill said. "It is hard to keep that momentum going throughout the season.
"Spurs have been absolutely fantastic but it is tough to keep it going every single game, week in, week out," the defender added.
"You will always have a blip in the season and maybe theirs has come now.
"We are at home, where we have some confidence now, and we are looking to get the positive result we need."
Roberto di Matteo, Chelsea's caretaker manager, will hope to have captain John Terry available after the centre-back missed the City defeat because of a knee injury.
Spurs have also been beaten at City as well as United, Arsenal, and Everton. They did record wins over Wigan and Newcastle, the latter by five goals, but Wednesday night's 1-1 draw at home to Stoke, which required a stoppage-time equaliser from Rafael van der Vaart, was another missed opportunity.
Tottenham manager Harry Redknapp has been busy insisting his installation as the favourite for the vacant England job had nothing to do with his side's loss of form.
And he was saying the same thing after the Stoke game about the effect of the abandonment of the previous Saturday's FA Cup quarter-final with Bolton Wanderers, which was called off when Fabrice Muamba, the Bolton midfielder, suffered a cardia arrest on the pitch.
Brad Friedel, Tottenham's experienced United States international goalkeeper, was adamant the squad were not wilting under the pressure of expectation.
"We want to play well, we want to win but we all saw here last Saturday what pressure was," he said. "I've got three kids and raising them is far more pressure than a football match.
"I don't think it's about holding your nerve, it's about going out and enjoying yourself and expressing yourself because those are the type of players we have. It's continuing what we've been doing all season long. Sometimes you can play very poorly and win a game and then nobody says anything.
"But we've been playing really good football without getting the results we want. I'm not concerned at all and we will go into the Chelsea game confident, expecting a good result."
Spurs are hoping striker Emmanuel Adebayor and England winger Aaron Lennon will recover from injury in time.
Source: AFP
Source: AFP