Raphinha, speaking to France Football, admits Flick called him when his appointment was first confirmed.
He said: "When his arrival was made official, he called me and told me that I was one of the players he was counting on, without knowing me or having ever seen me train. This was very important in my decision to stay and allowed me to work in complete serenity to reach the highest level. I knew he would be important for the team."
Raphinha says he also had a good relationship with Flick's predecessor Xavi.
He said: "Although there were many rumours about my departure last season, he kept telling me that he was counting on me. If he hadn't been the coach of Barcelona, I wouldn't be wearing this shirt that I've always dreamed of wearing.
"Xavi was convinced that with hard work I would become an important player. I work a lot on the mental aspect to find the calm and confidence needed to do things well."