Barca won 2-0, with Garcia outstanding against his former club.
"The first thing I want to do is thank Joan Garcia. He is one of the best goalkeepers in the world. We suffered, but we took the three points, and that is a signal to La Liga," said Flick.
"I don't think he will ever forget what he experienced here, because he played for Espanyol. They gave him the opportunity. Now he plays for us, and today he was one of the reasons why we won," says Flick.
During the warm-up, García was met with banners and discontent from the home fans. But despite the pressure from the stands, Flick felt that his goalkeeper remained calm throughout the match.
"Of course I spoke to him. I saw how he kept his composure, as always. He was focused and convincing. The best teams have the best goalkeepers, and he is one of them," Flick added.