The Blues are currently four points behind second-placed Manchester City - whom they play at the Etihad Stadium on Sunday.
"If we get a positive result on Sunday then that opens it right back up," Cahill told reporters. "We're taking it one game at a time but we'll be looking to do that on Sunday.
"It'll be tough game away from home, but if we do get a positive result then obviously second place is within touching distance."
Chelsea will look to defend a 1-0 lead when they host Sparta Prague in the second leg of their Europa League last-32 tie on Thursday.