Barcelona midfielder Xavi was disappointed by his side's finishing in the first leg of their Copa del Rey semi-final against Real Madrid.
Cesc Fabregas opened the scoring for Barca after the interval, but they missed several chances to extend their lead, and eventually saw Raphael Varane help Real to a hard-fought 1-1 draw.
"We let them off. I think we were the better side, we dominated and we created more scoring chances. It's a strange feeling," Xavi told the club's website.
"We have been creating plenty of chances in recent Clasicos, but we aren't accurate enough in front of goal. Scoring goals is key.
"Everything is still wide open. It will be the same story in the return leg, but we'll try to be more effective."
The second leg is scheduled to take place on February 27.