The Swansea City defender believes the Swans should have won all three derby clashes from last season and in particular looks back on a penalty decision at Ninian Park claiming the referee got the call wrong in the heat of the moment.
Speaking to the Western Mail, Williams said “We should have won all three games last year.
“But especially that game at Ninian Park – that penalty decision still grates on me to this day.
“I’ve not spoken to anyone since that day who thought it was a penalty or even questionable – just that it was a ridiculous decision.
“And for the game to finish on that ruined a good match. Not only that, it could have proved vital with the way the season panned out.
“Referees have a hard job and important decisions have to be made so quickly – but you want those key decisions to be correct.
“Emotions can run high in games like this and I’m sure there will be plenty of fouls and niggles on Saturday because of the size of the game. We have to have a strong referee.
“The first derby last year was the best atmosphere I’ve ever played in – hopefully we can repeat that on Saturday.”