Swansea boss Paul Clement accused Manchester United's Marcus Rashford of having "deceived" referee Neil Swarbrick to win a penalty in the 1-1 draw between the sides at Old Trafford.
Swarbrick awarded the spot-kick, which was converted by Wayne Rooney to put United ahead, after Rashford went down in the box in first-half stoppage time as Lukasz Fabianski dived at his feet.
Replays indicated Rashford was already on his way to the ground before there was contact between him and Fabianski.
When asked about the incident after the game, Clement said: "Replays show the player deceived the referee - there is no other way to look at it.
"You could say he has dangled a leg to get the contact, but he is (going) down before that, before there is any kind of contact."
He added: "Lukasz was furious. He said he had gone down to get his hands on the ball, could see he couldn't get it so came away from it, and that he (Rashford) had gone down before the contact."
Clement said Swarbrick, who delayed briefly before pointing to the spot, had told him he had been "sure what he had seen" - something the Swans boss believed was not the case.
"At the time, I looked at the reaction of my players first of all, and they were furious about it, so that puts a doubt in your mind as to whether it was the correct decision," Clement said.
"Also, the delay between the contact and the decision being given - there was a brief pause which normally would say there is doubt.
"The referee said to me after the game he was sure what he had seen and was just confirming with the assistant. I don't know why he even asked him, because he is almost as far away as I was.
"I don't know (if Swarbrick guessed). I just felt there was doubt - I don't think he was sure.
"I only know myself, and if I'm sure about something, I don't check with my assistants. I make the decision. That is it."
Clement feels officials should be assisted by video technology when making decisions over such incidents.
"For me, it has to be done," said Clement, whose relegation-threatened side equalised through Gylfi Sigurdsson's 79th-minute free-kick.
"For me it is unbelievable that in this day and age, with the technology we have available, that the only people that don't get the help are the ones who most need it.
"We can see it, you can see it, the fans can see it, everybody can see it - apart from the officials. It has to be done. It is long overdue."
Having claimed a deserved point, Swansea remain 18th in the Premier League table, two points adrift of 17th-placed Hull with both sides having three games left.
Clement said: "I'm very proud of my players today. We had a good result last week against Stoke (a 2-0 home win, their first victory in seven matches) and going into that we hadn't been playing well, we weren't picking up points.
"I think we really turned a corner last week and showed that again today.
"I think we showed a lot of different qualities - that we can come to a difficult place, actually take the ball and play well and create some good chances, and then also deal with a goal going in against us in difficult circumstances.
"We didn't feel sorry for ourselves, we got on with the job and I think when our goal went in, the least we deserved was that."