History would suggest that Wales will be up against it Down Under, having not beaten Australia on their own turf since the 19-16 triumph in Sydney in 1969.
However Williams is full of belief that they will change this month and has seen his eye caught by Blues wing Robinson, who he came up against with the Barbarians on Saturday.
Robinson scored Wales' first try as they ran out 30-21 winners and Williams, who was playing his last-ever match, insists the Australia tour can be groundbreaking for both player and country.
"It is going to be tough," said Williams - who scored the try that saw Ospreys lift the RaboDirect PRO12 title in his last-ever club match.
"It is a big ask to win the series against Australia - one of the best sides in the world - on their home turf but I think that is where we need to get to now.
"We've won the Grand Slam and we need keep going on an upward curve. I do see Wales winning a Test out there - whether or not they win the series I don't know.
"But they have certainly got a good enough squad and Harry had a fantastic game against us. He scored a try early on, and I was chuffed for him.
"He worked hard throughout the game, and for a young guy he didn't show that he was intimidated whatsoever. He took his chance well.
"I told him after the game I was chuffed to bits for him. He has come into a Grand Slam-winning squad and he was under a lot of pressure.
"So for him to go out and play like he did shows he has got a mature head on him. He made a big impact.
"He made some great breaks. He was all over the park, and that is what you want. I hope he gets lots more chances, and I am sure he will after his performance."
63x46.png){kind=logo}