Fifth-placed Chelsea trail Spurs by five points with nine games remaining following Wednesday's loss to Manchester City but Harry Redknapp's once high-flying men are winless in four matches ahead of their trip to Stamford Bridge on Saturday.
Cahill said: "Arsenal are having decent form and Spurs have been hit the last few games. 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. You'll always have a blip in the season and maybe theirs has come now."
Spurs have a notoriously poor record at Chelsea having not won at the home of the west London club since 1990.
Cahill added: "We're at home, where we have some confidence now and we are looking to get the positive result we need. We have built some momentum of late and the camp is positive at the minute."
January signing Cahill, looking increasingly assured in the Chelsea side, put the Blues ahead at the Etihad Stadium with his second goal in two games.
But the introduction of City's controversial striker Carlos Tevez, for his first appearance in six months, just moments later turned the tide. The hosts levelled with a Sergio Aguero penalty after Michael Essien was adjudged to have handled and then won it five minutes from time after the impressive Samir Nasri combined with Tevez to score.
Cahill, 26, said: "We were unlucky but we can't let it affect us because we have huge games coming up."
The defeat was Chelsea's first in five games since Roberto Di Matteo took over as interim coach following the departure of Andre Villas-Boas and, despite his disappointment at the result, Di Matteo did not think his side's top-four ambitions were badly damaged.
The Italian, who unexpectedly preferred Fernando Torres up front to Didier Drogba, said: "We are closer to third than we were 10 days ago, we still have the confidence we can make it. I always said we would like to finish at least fourth and that's what we will try to do, if we can do anything more it's a bonus."
Source: PA
Source: PA