David Moyes' side have lost only once in their last five visits to Stamford Bridge in all competitions and Cahill feels Everton will need to put in a gritty display there to turn their league form around.
"When we are up against it we seem to shine a bit and try and fight our way out of a corner - the main thing for us it to keep the unity and keep the strength on the pitch," the Toffees' Australia international told evertonfc.com.
"We need to have the determination and grit to go to a place like Chelsea and get the right result.
"We know they've been banging in the goals left, right and centre but we need to focus on our strengths.
"Past performances count for nothing and it's about how we apply ourselves in this game.
"It's exciting - Chelsea are one of the biggest teams in the country if not the world and for us it's a great challenge to go there and put in a great performance."