Real Madrid midfielder Casemiro says they must learn from defeat to Cadiz.
The newly-promoted side led 1-0 at the break thanks to Choco Lozano's goal.
Casemiro said, "We have to look at the mistakes, but the attitude in the first-half was not good enough and we've lost three points against a very organised side who knew exactly what they had to do on the pitch.
"We have to forget about it because we now have a Champions League week and it's important for us to start well as it's a very long and hard week.
"There's always room for improvement, but in the second-half they didn't have a shot on goal. We have to keep working hard, improve in attack and defence, and make sure we learn from it so that it doesn't happen against this season."