FIFA virus, anyone? Luka Modric left Croatia's match against Italy in the 26th minute holding his groin. It's obviously too early to tell how bad this injury is, but to see Modric leaving the field is never a good sign. Furthermore, muscle injuries are always really hard to nurse, so Real Madrid will need to play this safe and wait until he completely recovers from this injury.
At least, Isco has been playing so well lately that Ancelotti will likely consider to start him alongside Toni Kroos and James Rodríguez, and while Isco doesn't have Modric's defensive skills yet, Real Madrid's next games should be manageable enough with that midfield trio.