Hannah Bluck's try on debut for Wales helped her side survive a late onslaught from Scotland in a thrilling opening to the 2018 Women's Six Nations.
Looking for revenge for last season's 15-14 defeat in Scotland, Wales started brightly and earnt a first-half lead thanks to tries for wingers Jess Kavanagh-Williams and Bluck.
Scotland full-back Chloe Rollie fired a try back after the break, with Kerin Lake responding for Wales before Rollie grabbed her second with a wonderful effort.
10 minutes from time Jade Konkel burrowed over to ensure a tense finish, with Lana Skeldon's conversion cutting Wales' lead to 18-17, but Scotland couldn't complete the comeback and left the Welsh side to celebrate a memorable win.
The home side started in dominant mood and got the first opportunity to score following a powerful scrum, with full-back Jodie Evans hitting the post with her shot from the edge of the 22.
Wales weren't to be denied for long though and got the opening score on 11 minutes when excellent hands down the left saw Kavanagh-Williams find space and step inside for the try.
Scotland were struggling to get a foothold in the game and soon found themselves 8-0 down after being penalised for holding on just outside their 22, with Evans making no mistake this time.
But the Scots roared back and almost had the ball over the tryline, only to fall inches short, with Wales getting their second try on the stroke of half-time, Bluck finishing neatly in the corner.
After the break though Scotland spurted into life, with Rollie being put into space towards the left flank and cutting inside the last defender to touch down in the corner.
Rowland Phillips' side forced their way back into things, almost scoring with a succession of drives on the opposition line and eventually finding their way over with Lake going in almost unopposed.
But Scotland refused to be killed off and on 63 minutes got back into the contest with an excellent try, Lisa Thomson cutting a direct line before floating a pass out to the left for Rollie to complete her double.
Minutes later and Wales' lead was reduced to 18-17, with Konkel crossing the line with a pick-and-go and Skeldon adding the extras.
Siobhan Cattigan entered the fray to earn her first cap, though she watched her teammate Jodie Rettie see yellow in the closing stages.
There was still time for Kavanagh-Williams to miss out on a late opportunity before Wales put the seal on a crucial first victory of the Championship.