Six Nations/ Scotland v Wales: Wales will stand on the brink of greatness in Edinburgh tomorrow. Their progress in the past two years is simply measured. In 2003 the Red Dragon contingent arrived in Edinburgh fearing a whitewash and left facing one. They will run out at Murrayfield with a first Grand Slam since 1978 in their sights, a championship decider against Ireland in Cardiff six days away, and expectations rising feverishly in the valleys.

If Wales coach Mike Ruddock has remained cautious since his side opened their account against England five weeks ago, that is understandable, given the speed with which emotions can turn in the principality. This week he remained downbeat, and his side's recent record in the Scottish capital gives him good cause: Wales have won once in Edinburgh in the past 20 years.

Among the Welsh players echoing their coach was the wing Shane Williams. "I know a lot of people who are going up to Scotland expecting us to win. It's going to be a battle, but a different challenge from what we've faced so far in this Six Nations. Scotland are going to be very forward-orientated. They've got a good set-piece game, and we are going to be tested there. We have got to nullify that if we want to play some rugby ourselves."

Ruddock, however, feels his forwards have been equal to the task in this championship. "We have never said we are world-beaters up front. But we are starting to compete with the bigger packs. Everyone thought England might roll us over. Italy, well there was talk of them rolling us over, and so it's gone on.

"Against France last season we won 10 out of 27 set-pieces. This season, in France, we won 23 out of 30. There has been an improvement. We have pushed France, New Zealand and South Africa off the ball. We created three not-straight lineouts on French ball last week because of our pressure."

If Wales take their winning streak to four out of four, Ruddock will become the team's most successful Six Nations coach. His backline has been reshuffled, following the thumb injury to the captain Gareth Thomas in Paris, with Kevin Morgan coming in at fullback and Rhys Williams replacing Hal Luscombe. Together they form a back three one Welsh paper has nicknamed the "Diddymen".

The pack, however, remains intact, with Michael Owen standing in for Thomas as captain, as he did in the cliff-hanging second half of epic defence in Paris.

Whatever the past may indicate, on form there should be no doubt about the outcome. Nothing Scotland have done in this championship, apart from the opening few minutes against Ireland, has suggested they can do anything more positive than merely make life difficult for the opposition.

Wales, on the other hand, travel with richly deserved victories against England and France behind them, and the most successful try-scorer in this championship in the unlikely shape of their loose forward Martyn Williams.

Scotland delayed their team announcement until yesterday, when it was confirmed that, in their only change, the 22-year-old Rory Lamont will earn his first cap in place of Simon Webster on the wing. Lamont's brother Sean was Scotland's best player on the opposite wing against Italy two weeks ago and the duo are the first brothers in the same Scotland team since John and Martin Leslie three years ago.

Yesterday at least one train from Cardiff to London was delayed because of the estimated 40,000 Welsh fans setting off for Scotland, while others into the Welsh capital contained partygoers already looking to make a long weekend of it. These are merely hints of the frenzy that will be unleashed if Wales rise to expectations tomorrow.

Guardian Service