Internazionale coach Roberto Mancini was again disappointed for defensive mistake in his side's 2-1 defeat at home against Wolfsburg.
The Nerazzurri needed to score two goals without a reply to qualify for the next stage of the Europa League.
But they struggled to cope with a well-organised Wolfsburg side, suffering yet another home defeat in the campaign.
"We are disappointed, I can understand the boos," Mancini told Mediaset Premium.
"We created chances to score but at the same time we gave away chances of our own.
"It was a difficult game because we had to score two without conceding any. And our problem is that we simply cannot keep a clean sheet. We keep making mistakes although I believe that at the end of the day Wolfsburg is a better team.
"But we look forward, these are moments where the team has to grow."
