The 26-year-old has made clear his desire to leave White Hart Lane this summer, and the Croatia international has been fined twice in the past fortnight after refusing to participate in a training session before failing to turn up for Spurs’ tour of America.
The La Liga champions are yet to meet Tottenham’s valuation for the playmaker, but Casillas is confident Modrić would be a good addition to José Mourinho’s squad if the Croatian moves to the Spanish capital.
“I know him,” the Spain goalkeeper told AS. “He has been a great player ever since he signed for Tottenham. I faced him in the Euros and he had a very good season.
“If the manager thinks he ought to be then I am sure he will be at the level of this squad. It is not our responsibility to say anything more.
“The club and the manager are those that decide what is best for the team to move a step forward.”
Casillas, who captained Spain to Euro 2012 glory in July, revealed Madrid’s target for next season will be to defend their La Liga crown, while also reaching the Champions League final.
“Our goals are similar to those last year. We are hoping to move a step forward like we have in the other seasons since Mourinho has been with us,” he added.
“We want to win the league again, the Super Cup and then after two years of arriving at the doors of the Champions League final, we want to reach the final of Europe’s main competition.
“I think we have extraordinary fans, a magnificent stadium and an incredible squad. With all of this it is clear that this team deserves a European Cup, but there are many teams fighting for this title.
“There are steps we have taken. For example, two years ago players like [Mesut] Ozil or [Sami] Khedira didn’t have the experience they have now.
“The same applies with Karim [Benzema]. But thinking about the 10th European Cup is not an obsession because we face the start of the league and the Super Cup first.”
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