Shane Williams: Why I worry for Wales in Edinburgh showpiece

Wales usually expect to win in Scotland, but I think this month's trip to Murrayfield could be the toughest game of the Six Nations for Rob Howley's side.
Looking ahead to this year's fixtures 12 months ago, the focus would have been on the visits of England and Ireland to Cardiff.
But when I look at the way Scotland have evolved in the last year, I see a dangerous side which should worry Wales. The game in Edinburgh is a very tough one to call.
Scotland have been impressive for a while now. If you go back just two or three seasons, they weren't offering much behind the scrum. There was no continuity in their back division, no real structure, and they were forced to play a forward-dominated game.
But things have changed out of sight for them in the last 12 months. They're now playing some brilliant attacking rugby and have five or six potential Lions in their side. I've been hugely impressed with some of their play and it was only a matter of time before they took a scalp.
They did that on the opening weekend by beating Ireland and for me, that result was on the cards – it wasn't an upset you couldn't see coming. Scotland are now a very good side and a lot of their success is based around a Glasgow team which is having an excellent season.
Guys like Finn Russell and Stuart Hogg have been hugely impressive for the Warriors – some of their results in the Champions Cup, particularly their thrashing of Leicester, have been excellent.
Transferring that form to the national team gives Scotland the sort of continuity which would benefit any side, and other key men such as Tommy Seymour and Alex Dunbar have been on fire, too.
It's taken time for Scotland to get their attacking structure going, but you only had to look at the first half of their game with Ireland to see the danger they pose. They ran the Irish ragged, scoring some great tries with Hogg, Russell and Greig Laidlaw impressing.
That's the best thing about this year's Six Nations – almost everyone could end up being a possible British Lion. Laidlaw's name wouldn't have been in the mix for the scrum-half position a month ago, especially with Conor Murray, Rhys Webb, Ben Youngs and others around.
But his superb performance against Ireland has immediately put him in the frame. I think Laidlaw is an excellent leader – he really galvanises his side and kicks goals from anywhere. That's something Wales will need to watch out for at Murrayfield: concede penalties and Laidlaw will punish them every time.
It's not often you can say Scotland have some of the most in-form players in the Northern Hemisphere, but that's the case right now. Hogg for me is already on the Lions plane to New Zealand, probably as first-choice full-back, Laidlaw is up there, too, at nine and Russell is the sort of playmaker coach Warren Gatland would love to have in his side.
Then you've got Seymour, who is a very good player. I've watched him a lot as a former winger and his work rate is phenomenal. He's had an incredible season with Glasgow and the Wales defence will need to keep a close eye on him.
All of the above means I'm worried about Wales' trip to Murrayfield. In all my time playing I never lost there at international level, so unsurprisingly, I've got great memories of the fixture. It's one the travelling fans really embrace and it's a great occasion for everyone involved.
That will be the same again this year, but on the field I really expect a game with a difference. It's a huge match and a potential thriller given the amount of talent on show in each back line.
I've made it clear for a while now that Wales need to evolve their attack, and to their credit they're trying to do that. The second half against Italy was promising, but it took only 20 minutes against Ireland for Scotland to show Wales the way. They were prepared to play running rugby from the off, stretch the opposition, and score tries. I only wish Wales would be so daring.
Vern Cotter must take a lot of credit for their turnaround and while it's slightly strange to see him leaving when Scotland are on an upward curve, he will move on with his team in a good place.
Cotter's situation with Scotland reminds me a lot of Graham Henry and Steve Hansen with Wales. They struggled initially and then began to get the structures in place to be successful, only to move on to other jobs.
That's the way coaching works sometimes, but Scotland won't be any worse with Gregor Townsend in charge. He knows the players so well from Glasgow which means he'll fit in easily enough. The future is looking positive if you're a Scottish fan.
As for the here and now, I've made it clear I expect the game with Scotland to be very tight, but I'm still going to predict a Wales win.
I thought the Welsh pack got stronger and stronger against Italy, which for me was a positive sign. Scotland, on the other hand, tired against Ireland and while they deserved to win, they were hanging on at the end.
Though it's far from a foregone conclusion, wouldn't it be great if this game turned into a classic? It's certainly got the potential for it.
Just look at the possible respective back threes: Leigh Halfpenny, George North and Liam Williams up against Hogg, Sean Maitland and Seymour. That's one to get the pulses racing and, hopefully, we'll see a game played with width, high tempo and intensity for the full 80 minutes.
And while, as I said, I think that Wales will edge it, it's great to see Scotland back as a Championship force.
That might not be good for Wales a week on Saturday, but it's a huge positive for the tournament overall.