The two teams were paired in the round of 16 draw on Friday.
Butragueno said: "CSKA Moscow proved to be a dangerous side by defeating Inter in Milan and by eliminating Lille, who won the Ligue 1 last season. You never know in football. They have young, talented and fast players.
"We'll have to watch out because we'll play the first leg in February, when the temperature is very low in Moscow. We must focus on each game at a time because a bad night can get you thrown out of the championship. We have a great team and our players are performing very well this season."