The Iceland manager was appalled at some of the decisions made by official Alberto Undiano as Olafur Skulason was dismissed in his side's 0-0 draw with Croatia on Friday
The home side was reduced to 10 men just five minutes into the second half when Olafur Skulason was shown a straight red for appearing to pull back Ivan Peresic, but a spirited defensive display ensured they travel east next week with a firm chance of making it to Brazil next summer.
The Swede applauded the resilience of his team in holding on for a draw, but was disappointed in the referee’s decision which tilted the game in the visitors' favor early in the second half.
"Tonight the referee was not at his best," Lagerback told reporters. "I am pleased with the way the players stood up, but we were unlucky. I did not see a red card from my position, but there were many situations where he [Undiano] did not know what he was doing.
"There were a lot of 50-50 decisions that were not in our favor. I've seen him a few times and I felt he had a bad day. I also have bad days. That's life."
Lagerback's men travel to Croatia on Tuesday having lost just one game on their travels in qualifying - a 1-0 defeat to Cyprus in September 2012.