Lleucu George kicked a last-minute conversion to break Scottish heats and give Wales their first win of the Championship in a 17-15 victory.
Scotland managed two tries in the first-half through Jade Konkel and Sarah Bonar but a Bethan Lewis score and accurate kicking from Robyn Wilkins meant the teams went in the break tied at 10-10.
A quiet second-half burst into life in the final five minutes as Chloe Rollie slid in to give Scotland a five-point lead but it only served to ignite the Welsh fire and after Siwan Lillicrap went over in the dying seconds, George added the two points to seal victory.
After taking command of the game from the kick-off Scotland used a tap and go to their advantage and put the first points on the board via Konkel who scored her seventh try in Scottish colours.
Lana Skeldon’s conversion attempt was not helped by the strong winds at Scotstoun as she put her first attempt at goal wide.
But the adverse conditions didn’t stop Robyn Wilkins from posting Wales’ first score from the tee to keep Scotland well within their grasp.
And moments later Bethan Lewis drove over the line to score her first ever try for while Wilkins made it a maximum score.
It was all about the forwards for the opening 20 minutes as no sooner had Wales taken the lead than Scotland levelled things up with Bonar peeling away from a driving maul to dot down.
A stunning kick to touch from George gave Wales the platform to attack from close range and Lillicrap thought she taken advantage of it before the TMO intervened to rule out her try attempt.
After the teams emerged for the second half the game morphed into a cagey affair with most of the rugby being played in the centre of pitch leaving opportunities for tries few and far between.
With five minutes to go Hannah Smith took the ball in hand and ran at the Wales defence, breaking through an initial tackle and offloading to full-back Rollie to sprint home and give Scotland a five-point buffer.
But heartbreak was on the horizon for Scotland as Wales used the try as motivation for themselves and laid siege to the Scottish defences, eventually breaking through via Lillicrap who had her try this time.
As the clock ticked into the red, George lined up the kick to win the match and after short pause for composure, nailed it through the posts to seal Scotland’s fate.