Need help! Barcelona vs Granada tickets

Hello friends. My name is Leonardo and I'm from Sao Paulo, Brazil.

I will be in Barcelona in late October and want to go to Camp Nou to watch Barcelona vs Granada. I tried to buy a ticket on Barça website, but it was not possible. The company that manages the sells tickets (entradas.com) sent me this message:

"Good afternoon, Leonardo.

I fear that, for security reasons, our website don´t allow you to buy tickets from your country or using credit cards issued in your home country.
Try buy directly at the box office stadium itself.

We feel sorry.

Regards "

My question is: is there any other way to buy tickets online? Please, you guys have any suggestions to help me?

Thank you very much in advance.

Like I said in the other thread, try ticketmaster.es. I had no problem buying tickets there using my credit card (certainly not issued in Spain).