Stephen Jones kicked three penalties to keep Wales in the fight for the best part of an hour but Chris Paterson inflicted the damage to seal Wales's fate. The Scotland captain kicked seven penalties from as many attempts after his side had dominated possession and territory throughout the game.
The result leaves Wales still waiting for their first win of the Championship and now they must pick themselves up for the prospect of France in Paris in two weeks.
Coach Gareth Jenkins had made four changes to the side that pushed Ireland so close just six days earlier and the move looked to have worked when Ryan Jones went close to scoring the game's opening try on twelve minutes. Yet the British Lions No.8 was penalised for holding onto the ball just a yard from the Scotland line, which set the tone for the rest of the game.
Scotland dominated the line-outs and scrums and it was only due to a brave defensive effort from Wales that the hosts were kept out. Mark Jones marked his return from injury with a series of crunching tackles, including a challenge on Paterson that saved a certain try after twenty-two minutes.
Wales were poised to attack in the second half after trailing 9-6 at the break. However, Scotland came out firing on all cylinders in front of their home crowd and Wales were forced to spend the next forty minutes on the back foot.
Tom Shanklin returned from a month out due to injury, replacing James Hook at half-time, but that was not enough to save Wales. Scotland got the better of the exchanges up front, despite the best defensive efforts of Alix Popham, and Paterson knocked over the points as the pressure told.
Wales's fading hopes of a comeback were finally dashed on fifty-seven minutes when hooker Rhys Thomas was shown the yellow card for a professional foul. Paterson successfully slotted the ball between the posts to give Scotland an 18-9 lead.
Dwayne Peel, who led out Wales on his fiftieth cap, tried his best to galvanise the Welsh attack but the non-stop tackling had taken its toll on the Welsh players and Paterson had the last say with his seventh penalty two minutes from time.
RBS Six Nations 2007
Scotland 21 Wales 9
Scotland: H Southwell; R Lamont (N Walker 70), M di Rollo, R Dewey, C Paterson (capt); P Godman (S Webster 69), C Cusiter (R Lawson 73); G Kerr (A Jacobsen 55), D Hall (R Ford 67), E Murray, J Hamilton (N Hines 48), S Murray, S Taylor, K Brown (A Hogg 55), D Callam
Replacements: R Ford, A Jacobsen, N Hines, A Hogg, R Lawson, S Webster, N Walker
Wales: K Morgan (C Sweeney 45); M Jones, J Robinson, J Hook, C Czekaj; S Jones (capt), D Peel; D Jones (G Jenkins 58), R Thomas (M Rees 67), A Jones, R Sidoli (I Gough 52), A Jones, A Popham, M Williams (J Thomas 67), R Jones
Replacements: M Rees, G Jenkins, I Gough, J Thomas, C Sweeney (K Morgan 52)
Referee: Alan Lewis (Ireland)