Fourth-placed Hibs have four points from their last seven games and put in a desperate performance in losing 1-0 to Ross County on Wednesday.
McPake describes Celtic as "frightening" at their best and is well aware Hibs' top form is required for them to have any hope of improving on the 2-2 draw at Parkhead earlier this season.
McPake said: "Celtic are the best team in the country, no doubt about that. On their day they can be frightening.
"We proved when we went to Celtic Park that we can be a match for them.
"I think our biggest problem will be which Hibs team turns up.
"We've got to make sure that when we take to the pitch on Saturday we play the way we had been playing earlier in the season.
"If that happens then it should be a good game."