The 25-year-old left Real Madrid for QPR in the summer on a four-year contract and says that playing for the London club is "a perfect challenge" for him.
"He (Juan Mata) encouraged me to come here and had good words to say about Queens Park Rangers," said Granero.
"I was born in Madrid, grew up in Madrid and I had the chance to spend my whole life in Madrid," he added. "But I wanted to enjoy football, I have always been very competitive. I want to compete against myself — and the way to do that is to set yourself a great challenge.
"This (QPR) is a perfect challenge for me — this team, this club, this league, this country. It's a perfect fit from my point of view and with a big challenge like that I was always going to be happy."
QPR will host Everton at Loftus Road in the Premier League on Sunday.