The left-back thinks his former club-mate has joined the Spanish club ahead of Manchester City and says the midfielder possesses everything needed to succeed in the capital
The young attacker is the subject of a transfer tug-of-war between the Spanish club and Manchester City, however Manuel Pellegrini's side are willing to pay Malaga £20 million plus £10m add-ons for the 21-year-old.
But Monreal, who played alongside Isco between 2011 to 2013 at La Rosaleda, says his compatriot has snubbed Pellegrini's approaches for a move to the Bernabeu.
"Isco has succeeded wherever he has gone. I believe he has already signed for Real Madrid and I'm sure he'll do very well because he is a great player," the 27-year-old told Marca.
"He may cost them, but together they will have opportunities and they will seize them."
A victim of Real Madrid's revolution will be Gonzalo Higuain, who is on the verge of securing a move to Arsenal. Monreal, however, has welcomed the arrival of the Argentine at the Emirates Stadium.
"I would love it. Higuain is a part of football, and I always loved how he played for Real Madrid. He is a scorer and would be a reinforcement that we could really use," he continued.
"Arsenal are one of the biggest teams in England and this summer they are working towards good signings to break that [trophy-less] streak."