Aberdeen slipped four points behind Motherwell after the visitors claimed all three points in a poor game at Pittodrie.
It was a night to forget for the Dons who failed to show any real attacking impetus with Liam Donnelly’s first half header giving Stephen Robinson’s side a vital win.
Aberdeen manager Derek McInnes made two changes for the visit of Motherwell with Bruce Anderson and Connor McLennan dropping to the bench.
Lewis Ferguson, who missed Saturday’s Scottish Cup win against Dumbarton due to suspension, returned while there was also a starting role for Jon Gallagher.
Motherwell made two changes for the trip to Pittodrie. Liam Donnelly and Liam Grimshaw came into the starting line-up with Richard Tait dropping to the bench while Jermaine Hylton missed out.
Aberdeen may have been wasteful in front of goal in their Scottish Cup win against the Sons on Saturday but they struggled to create chances in a poor first half against the Steelmen.
Andy Considine’s shot from a Sam Cosgrove flick on, which was saved by Mark Gillespie, was the only chance of note from the home side and it was the visitors who carried the greater threat.
Chris Long tested Joe Lewis before limping off on the half hour mark before his replacement Christian Ilic also tested the Dons captain.
The warnings were not heeded, however, and Well broke the deadlock in first half stoppage time when Donnelly headed a Liam Polworth free kick past Lewis to give Well the interval lead.
Aberdeen, as was the case in the first half, huffed and puffed without getting anywhere in a disappointing second half.
Ryan Hedges, Bruce Anderson and Curtis Main were all sent on in an attempt to rescue something from the game but Well stood firm to deny the Dons any clearcut chances in what was a forgettable affair for the home side.
