"We have lost one game in 43 home European games. An accident like that can happen," he insisted.
"At West Ham, we looked outstanding going forwards, dynamic and then suddenly had two flat performances. It is difficult to explain.
"We have hit the wall a little bit in the last two games, and just did not find our rhythm.
"But we have to just focus again on the quality of our game, the way we want to play, and not concede too much against who we play.
"With the quality we have, the results will come back."