Roberto Martinez says Villa are "one of the best sides on their day" as he praised Paul Lambert's managerial approach.
Martinez pointed to wins over Arsenal and Man City as major reasons for the respect he holds for the claret and blues.
Everton boss Martinez also hailed Lambert's tactical nous and his transfer policy of signing young, hungry starlets.
He said: "We won't underestimate their quality, that's for sure.
"Anyone that can beat Arsenal or Manchester City deserves huge credit.
"When they have everyone fit and available, they are as good as anyone on their day.
"They have a lot of young players which shows a lot of bravery - that brings you energy and sometimes a dangerous naivety, which is sometimes needed in the modern game.
"We know what we are going to face on Saturday.
"They have had really difficult games so far. I think it's fair to say they are a very brave team, very flexible tactically.
"They always cause a threat and try to win the game, which is refreshing at times.
"I always have great admiration for managers who can be flexible with their tactical approach. Clearly, Paul Lambert has achieved that at Villa."
Villa should have Christian Benteke back fit for the Toffees clash, with Gabriel Agbonlahor and Andreas Weimann also turning in some impressive showings this term.
Martinez added: "You look at Villa in terms of energy, the way they are set up and the way they can be flexible and organised. Their front three have incredible understanding and threat.
"It makes for a dangerous side and, unless you are at your best, you cannot compete at Villa Park this season."
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