De Boer took a similar approach when his side faced Manchester United at Old Trafford in the Europa League last season and was rewarded with a 2-1 win, although his side lost the tie overall.
He said: "We showed it last year against Manchester United.
"I think this group of players have already proved they can do it and I am not worried whether they really believe it.
"I want to see players who play bravely with their own qualities and maybe better.
"That makes you a better player if you can play your best under the highest pressure. A lot of players will have that tomorrow."