Mijatovic says it's clear Real Madrid are a "different team" when they play in the Champions League.
He said after the 3-0 first-leg round of 16 win: "The theory that Real Madrid changes in this competition is confirmed.
"We see a weak Madrid in La Liga, but tonight... they gave a recital against a team with a lot of quality and a coach who has been in this for a long time.
"The team transforms and the same players who have doubts in other matches, become and demonstrate why they are Real Madrid players."
On Fede Valverde and his hat-trick, Mijatovic also said on El Larguero: "Real Madrid played without a striker, because it was a 4-4-2 with four midfielders and two other players moving freely.
"Valverde is a captain, a leader, and these matches will be very good for him to become a fundamental player for the future of Real Madrid."