Chelsea captain Cesar Azpilicueta insists Ross Barkley was confident to take a penalty against Valencia.
With the Blues down 1-0 at home, Barkley and Willian embarrassingly argued over who would take the spot-kick after Daniel Wass' handball.
Barkley won the argument but fired his shot over the bar to help Los Che seal a memorable away victory.
Azpilicueta told BT Sport: "It is hard to take because through the game we had better chances and controlled the game. It is the Champions League and it can be decided in small details. They score a goal and we could not convert our chances.
"Ross (Barkley) is one of the best penalty takers in the team and one who takes them. He had the confidence and he was unlucky hitting the bar. They [the other players around him] were encouraging him to have the confidence to score. There was high expectation. They were trying to get him into the best condition. Hopefully next time it goes in.
"We are trying to build something special. We have a young squad. But we need to get results straight away. It is a lesson we have to learn as a team. We still have five games to qualify."
