Antoine Griezmann didn't hold back after Barcelona were beaten 3-2 in the Spanish Supercopa final by Athletic Club de Bilbao on Sunday.
"We're pissed off, angry, annoyed... everything. Everything. When you lose a final all the feelings are bad ones," Griezmann told Movistar.
"We know Marcelino's teams work really hard, press really well. We made mistakes at dead balls and we will have to improve and work on them in the week."
Griezmann scored twice and his second goal, in the 77th minute, looked to have earned Barça a first trophy in the Ronald Koeman era.
However, Athletic equalised from a set play in the final minute of normal time and Iñaki Williams' goal in extra-time won it for the Basque side.
"It was a poorly defended play, we didn't speak," Griezmann added. "We must work on it, this week, and improve because these details are very important to see games out."