Zeman said: "It has been a bad weekend for referees. People say they don't decide tournaments, but I think on the whole they really can. Tonight Pablo Armero spat at Tachtsidis with the fourth official a few yards away, yet did nothing... For me, these things are decisive.
"We started very well, creating another three great scoring opportunities along with the two goals in the opening half-hour. After conceding with a push on Osvaldo that wasn't spotted, we got irritable.
"Udinese play very well on the counter-attack and we were unable to stop them, so we conceded another two goals with our horizontal passes intercepted.
"If you don't attack the ball straight away then you have problems. We ran backwards and it is difficult to defend like that. When we play our football and defend together, it is difficult to score against us."