Both Scotland and Wales can realistically still win this year's Championship, having won two of their opening three games but only the winner in Edinburgh this weekend will continue in the hunt.

After losing their RBS 6 Nations opener to England at Twickenham, Scotland have beaten Italy and Ireland to record their first back-to-back wins in the championship since 2001 - and Johnson insists his men harbour realistic ambitions of making it three on the bounce.

Only Stuart Lancaster's England can still win the Grand Slam but with the Red Rose heading to Wales and the Millennium Stadium on the final weekend of the Championships - Scotland and Wales can still take advantage of any slip-up.

It's a been a very similar tournament for both Scotland and Wales thus far - they both lost their opening fixture to Ireland and England respectively - but have since recovered to turn their form on its head.

Scotland were fortuitous last time out against Ireland at Murrayfield, edging a narrow 12-8 win despite being outplayed and dominated territorially for much of the last 80 minutes, while Wales won 26-9 in Cardiff in their last encounter.

But the challenge of Wales at Murrayfield this weekend is not a fixture Johnson fears as he knows exactly what to expect from the men from across the Severn Bridge.

"They haven't done anything different for five years and I like that personally," said the former Ospreys boss.

"Sides are confident enough to know what they are. It's about understanding what you are.

"It's as much about people and what they want to be and not deluding yourself.

"I'd like to be Brad Pitt, but the reality is different.

"I'm trying to avoid this up and down ride. Some days you won't be as good as the opposition. Sometimes you do that but I don't want us to have an identity crisis.

"Know what we are, know what we're good at and keep doing it."

Scotland have recalled prop Euan Murray in place of Geoff Cross, having missed out on the clash with Ireland as a result of his Christian faith, while Duncan Weir makes his first Scotland start, getting the nod at fly-half in place of Ruaridh Jackson.

It has not been all plain sailing for Wales in recent months, their first win of the season's Championship in Paris was a first win in nine matches for Wales, a first for Rob Howley as interim coach and a first since completing the Grand Slam last season, against France in Cardiff.

Wales have struggled with injuries, particularly in the second row, while the form and fitness of skipper Sam Warburton has also been a major concern.

Warburton was left on the bench last time out in Rome, Justin Tipuric was preferred in the back row, while Ryan Jones has skipper the Welsh side expertly in Paris and against Italy.

As a result Jones retains the captaincy for the trip to Murrayfield, despite Warburton returning in place of Tipuric in one of three changes made by Howley.

Elsewhere, Alun Wyn Jones comes into the second row in place of Andrew Coombs while Paul James replaces Gethin Jenkins, who has a calf injury, at prop.

"We are bringing in a wealth of experience with Alun Wyn and Sam and they both performed well off the bench in Rome," said Howley.

"Ryan has led the team to two wins and deserves to captain the side against Scotland.

"We have spoken a lot about momentum in this tournament and we go into the game with two wins under our belt but Scotland are in the same position and it's going to be a good challenge."