Newcastle manager Alan Pardew felt World Cup final referee Howard Webb made three errors which cost his side dear during their 3-0 defeat at Swansea.
The Magpies had travelled to south Wales on the back of a run of four straight wins, but they fell to a comprehensive defeat as Nathan Dyer and Jonjo Shelvey found the net either side of a Mathieu Debuchy own goal.
But Newcastle were aggrieved that Webb did not award them spot-kicks after Ben Davies appeared to handle a Loic Remy shot, and Yoan Gouffran went down after an aerial challenge with Ashley Williams.
Both incidents happened with the score at 1-0 and Pardew also felt Shelvey could have seen red after he appeared to aim a headbutt towards Debuchy during a heated exchange a few minutes before the ex-Liverpool man rounded off a superb individual display with a stunning, curling strike.
The Newcastle boss said: "Two big decisions went against us and that was crucial in the result.
"The first one was a penalty, no doubt in my mind about that. I felt that at the time and my players' reaction told me everything I needed to know, and that should have told Howard as well.
"It hit his arm and it's going in the back of the net. That's a penalty isn't it?
"Again the second was for a foul on Gouffran. I thought Williams had no chance of winning that header, he has gone into the back of Gouffran and he just played on.
"I was disappointed in those decisions. I've told him that as well. He has given me his explanation and I accept that, and I don't agree with it.
"Then there is the incident with Jonjo, looking at video highlights I think that was disappointing for Jonjo as I think he is a terrific lad and that's unlike him, but again maybe you could argue he should not be on the pitch."
Newcastle travel to Old Trafford to play Manchester United on Saturday.