O'Neill said: "It was an incorrect call in my opinion. It looked as though he tripped over his own leg, only he knows if he dived, but the assistant on that side didn't give it. It was down to the referee.

"It's very frustrating because we are in an environment where there are no fans and teams are claiming for everything and putting officials under pressure and they need to be stronger.

"If 20,000 fans are in the stadium tonight I can't see him giving that. I've watched it back three times and I can't see how the referee could say he is 100% certain.

"It's disappointing. We hit the post and bar and the least we deserved was a point."

An error from Marc Guehi gifted Stoke a sixth-minute lead when his pass was cut out by Steven Fletcher and Powell thumped his shot past the helpless Freddie Woodman.

The visitors were level after 19 minutes when Ryan Manning's cross was volleyed home by Roberts from eight yards.

Tommy Smith's vicious drive thumped a post just before the half-hour mark, while Manning was inches wide at the other end.

With 49 minutes gone Fletcher hit the bar from close range and James Chester ballooned the loose ball over, while Angus Gunn made a great save to deny Roberts his second as Swans pushed towards the end.

But the Welsh side's first win in Stoke in 20 years was confirmed with the late drama, as Ayew made it 11 for the campaign.

Swansea manager Steve Cooper said: "I'll be honest I haven't seen it back on the TV but I thought it was a penalty at the time. It certainly looked a penalty to me.

"You are hoping a winner will come and you never give up, you keep going and that's what happened.

"We got our chance with the penalty at the end, we were passing our way up the pitch and we had our wide centre-backs getting in the box to try to create. We were just keeping going and doing what we do and in the end it paid off with the last kick of the game."