Real Madrid midfielder Casemiro admits new contract talks could be difficult.

Casemiro has raised doubts over his future ahead of this week's Champions League round 16 second-leg clash at Manchester City.

Asked about his renewal in an interview with Esporte Interativo, the Brazilian answered with an enigmatic "it is a difficult question to answer".

"It is not time to talk about it, it is time to talk about Manchester City, we are thinking 100% about it. The club is in a complicated situation and at the right moment my agent will answer that question," Casemiro responded.

Needing to overturn a 2-1 aggregate deficit, the midfielder added: "They will not be able to count on the public factor and perhaps that may favor us a little, but the players are the same, the coach is the same and we all know that the difficulty is the same. They are also a great team."