Down 3-1 at the Camp Nou, Barcelona staged a remarkable comeback to win the game in the 98th minute, with Raphinha netting the winner from the spot.
Speaking to DAZN post-match, Flick was all praise for the Brazilian star, who's been on fire lately.
“When you win games like this, it's something you enjoy,” Flick said.
“It wasn't a surprise to suffer so much. They're a great team with a fantastic coach. We'd warned them about it in the press conference.
“Raphinha is very important. I love him, like the other players, but he's a leader. He always has that positive thinking that he passes on to his teammates.”