Ronald Koeman called Sunday's draw with Cadiz more disappointing than Tuesday's heavy Champions League defeat to Paris St Germain as Barcelona 's frustrations continued.
Alex Fernandez's last-minute penalty saw Cadiz snatch a point in a 1-1 draw at the Nou Camp after Lionel Messi had marked his club-record 506th LaLiga appearance with a first-half spot-kick.
The result saw Barca miss the chance to cut the gap to leaders Atletico Madrid - beaten by Levante on Saturday - to six points, and Koeman said the feeling was worse than after Tuesday's 4-1 loss to PSG in the last-16 of the Champions League.
"It is disappointing," Koeman said in comments reported by Marca. "These types of games have to be won and we did not. It was a great opportunity lost after the loss of Atletico. I am very disappointed, more so than on Tuesday.
"We could not afford to let two points get away. I don't like to blame individual players but we were not up to the task offensively and we have to defend differently. For our quality, we had to win."
Koeman said he had questions over the Cadiz penalty, awarded when Ruben Sobrino went down under a challenge from Clement Lenglet, but admitted Barcelona should already have put the game beyond reach.
"The lead was very narrow and they could equalise at any time, which is what happened," he said. "You leave the door open for them to draw at the end if you don't kill the game and score the second.
"It was difficult for us to create opportunities because they were behind the ball and there was no space. We lacked freshness in attack."
The draw leaves Barca continuing to trail both Madrid clubs but Koeman said there was still time for them to turn things around.
"We can still do something," he said. "There is no team that wins games easily.
"But we must recognise that opportunities like this cannot be missed anymore. I don't think it is unforgivable, but it was an opportunity to close the gap.
"(The league) is not more complicated than before. No team is unbeatable, nor are they going to win every game. There are still options. But we have missed two important points."