In atrocious, wet and windy conditions in the opening spell, the Steelmen endured the concession of an early goal by Aberdeen’s Christian Ramirez to recover to win thanks to first half strikes by Kevin van Veen and Connor Shields.
The victory has earned Motherwell a place in the quarter-finals, with a home tie against Hibs on the weekend of Saturday, March 12.
After another miserable day for Aberdeen – whose fans roundly jeered the team after the full-time whistle as they walked past them to get their dressing room in the Tommy McLean Stand – it emerged on Sunday morning that chairman Dave Cormack had taken the decision to fire manager Stephen Glass.
Yet this was a snenario that had seemed unlikely after just three minutes on Saturday when Ramirez got in between two defenders to head home a Ross McCrorie cross.
This came two minutes after Motherwell – and manager Graham Alexander in particular – were infuriated when Joe Efford’s ‘goal’ was ruled out for offside after he expertly shot home.
With the elements at their back in the first half, ’Well stormed back and equalised on 34 minutes when van Veen netted his fourth goal against Aberdeen this season with a deflected shot.
The hosts’ Sean Goss shot into the side netting before Liam Donnelly knocked the ball wide from close range after a Goss free-kick.
But it was 2-1 Motherwell in first half stoppage time when Dons keeper Gary Woods didn’t deal with a Goss corner and Shields netted a shot from close range.
’Well dominated the second half with van Veen denied by Woods before the Dutchman had an effort blocked by a defender after the keeper dropped a corner.
Efford shot just over and the returning Mark O’Hara went close with a long ranger before van Veen shot wide and had another effort saved by Woods.
Lewis Ferguson and Connor Barron went close for the Dons before home keeper Liam Kelly sealed the win with a wonder save from Ramirez.