Williams’ career achievements are considerable, including 84 Wales caps and two Lions tours, but victories against Scotland at Murrayfield are rare.

It has, in Williams’ case, only happened once in five attempts.

The omens can be considered good if Wales triumph next Sunday, given their last Edinburgh win was part of the 2005 Grand Slam season.

That 46-22 success remains Wales’ record win over Scotland - home or away - yet Williams’ other Murrayfield experiences amount to a draw and three defeats.

Since 1985, Scotland have made home advantage count eight times from 11 attempts, losing only twice and claiming a 28-28 draw in 2001.

When Wales last visited the Scottish capital two years ago, they lost 21-9, producing a listless performance Williams painfully recalls as “a nightmare”.

He said: “It was one of the worst games I’ve had for Wales.

“Nothing went right for us on the day and even Sid’s (lock Robert Sidoli) boots were falling off at one point.

“Our confidence and form wasn’t the best and, when you go to a place like Murrayfield like that, you get found out.

“This time we will be more confident but we know it won’t be a walkover.

“I remember being asked the question in 2005 before we went up there, ‘hands up who’s won at Murrayfield?’

“I think it was only Gareth Llewellyn who could put his hand up. We won that year but it’s the only time I have been on a winning team there.

“It is always a tough place to go and I think they are probably stronger than they’ve been for a few years.

“But momentum is massive. If you can get a good start, it has a snowball effect. We showed that last year.”