Ernesto Valverde was left ruing Barcelona's ineffectiveness in front of goal after their 29-match unbeaten run was ended by Espanyol in the first leg of the Copa del Rey quarter-finals.
Young Espanyol substitute Oscar Melendo secured the 1-0 victory for the hosts two minutes from the end with a neat finish, but Barca - who last lost in the Supercopa a Espana to Real Madrid in August - were left wondering what might have been in the Catalan derby.
Lionel Messi saw a penalty saved just after the hour mark and created a decent amount of chances in a game they dominated.
And Valverde believes their poor decisions in front of goal contributed to the defeat, while he also feels the penalty miss reinvigorated Espanyol and their supporters.
"Despite suffering in strategic situations, sometimes it seems that you suffer more because of the environment than the chances," Valverde told reporters.
"But their approach was to sit back and wait for us, closing any interior spaces. It was hard for us, but we had it under control.
"We were not successful in goal situations. The penalty save reactivated the crowd - there was some tension and then they scored.
"We wanted to do the same as always [in terms of the way they approached the game], but they defended well, they got it right in the move for the goal and Diego Lopez's penalty stop. We have to come back."
And Valverde feels that, although it is only a slender deficit, Espanyol are favourites ahead of next Thursday's return leg in Camp Nou.
"The favourite at the end is the one who is winning, who has an advantage, in the same way as when we drew in Vigo [against Celta in the last 16]," Valverde said.
"The result is not good for us. We have to play at home, but they'll try to score. It's the cup and you have to play until the end."