Northern Ireland manager Lawrie Sanchez admitted the Windsor Park fans had every right to boo the team off after the 3-0 Euro 2008 defeat to Iceland.
Lawrie Sanchez was depressed by Northern Ireland's defending
"It is the first time I have heard them do that but it was what we deserved today," said a deflated Sanchez.
"Really we froze again. Iceland wanted it more in the first half and got a three-goal lead. That was game over.
"It was poor defending and all the goals could have been prevented. Now we have to get the players up for Spain."
Sanchez claimed his side gave Eidur Gudjohnsen too much respect at Windsor Park.
"He is a world class player, who can make things happen," said the NI manager.
"We were meant to squeeze the space but we defended too deep and allowed him to play.
"I thought we were capable of winning this game but it boiled down to the team that wanted it more.
"That was Iceland and I am at loss to understand why. We had our backsides spanked."
Iceland coach Eyjolfur Sverrisson also highlighted the contribution of Gudjohnsen.
"Eidur is a really important player for us," said Sverrisson.
"He has a great attitude to the group. They are like old friends.
"He took care of the game for us with his ability."