McDermott watched Chelsea move 2-0 up and coast to victory against Wigan on Sunday and he has no doubt how hard it will be to overcome the Blues on Wednesday.
"They are the best team in Europe," McDermott said.
"I thought they were really, really good on Sunday.
"They started off really well. They got a couple of goals early on and could have scored another one when Fernando Torres went through.
"But it will be a great challenge for us tomorrow night."