Antoine Griezmann knows he's upset Atletico Madrid fans over the way he left for Barcelona.
Barca have paid 120m fee for the Frenchman.
Asked about returning to Atletico this season, he told Marca: "I know there will be whistling.
"It's part of football: they really loved me and when someone leaves, it can hurt.
"It was like that at Real Sociedad: my first visit back wasn't easy, but I will always have La Real and Atleti in my heart because they gave me so much."
