Gary Cahill lambasted referee Andre Marriner after he failed to penalise Leroy Fer ahead of Swansea's second goal.
Diego Costa had fired the Blues into a first half lead but the Belgian goalkeeper stupidly hurled himself at Gylfi Sigurdsson in the penalty area to concede a spot kick that the Iceland international dispatched with aplomb.
And, just moments later, Cahill was caught in possession by Leroy Fer who raced in to slot the ball past Courtois.
The England defender cried foul but Andre Marriner rejected his appeals and, even then, his poor first touch invited the Dutchman into challenge. With hindsight, Cahill would have played the ball straight to Courtois.
Costa equalised with an overhead kick but Cahill was fuming about the foul after the game.
He told the BBC: "It's a clear foul. I'm frustrated. Come on, seriously! You could be sat on the moon and see it is a clear foul. I took the touch away from him, he came through the back of me. It was clear as day and seeing it back has made me even more angry.
"It's all fun and games for the fans isn't it but it's the players who suffer. That kills me and kills my team. We have dropped two points which is massive in this league.
"Look at my face! It's incredible. I said to the referee there's three of you that can see that. There were two fouls, and between the officials they have said that they couldn't see it. For me that is incredible."
Cahill's complaint came just three minutes after Thibaut Courtois' rush of blood resulted in him fouling Gylfi Sigurdsson inside the box. The Iceland international dispatched the spot-kick with aplomb.
Manager Antonio Conte said: “The first goal, we must improve. It's normal. For the second goal, I think that everyone can see the the double foul on Cahill and I think that is a mistake of the referee.
“These things can happen to both sides. I don't want to complain about this but it is the reality. I want to see after this situation we had a fantastic reaction.
“I also want to tell them that this game, if we have a chance to kill it, we must do so.”