Derby manager Nigel Clough acknowledged two-goal Glenn Murray had been the difference after watching his side beaten 3-0 by Crystal Palace at Selhurst Park.
However Clough was unhappy with the way County conceded the opening goal, claiming his defenders had been illegally blocked off in the build up to Murray heading in Yannick Bolasie's 12th-minute corner.
He said: "There was a lot of blocking going on which happens but sometimes you hope that you just get a referee which sees it, sometimes you don't.
"But I can't have too many complaints, he's got a free header from eight yards out and having started quite brightly, we found ourselves one-nil down.
"But after all the talk of the widemen all week and their threat, he was the difference - the centre forward Murray. He was the one that caused us all the problems today."