An otherwise uneventful encounter erupted into controversy deep into injury time when Motherwell substitute Dirk Lehmann had a strong penalty claim turned down before Stephen Pearson was sent off for an innocous looking challenge.
It all ensured that Aberdeen held on for their second win at Fir Park this season and a badly needed victory after back to back losses against Dundee and Kilmarnock.
Referee Dougie McDonald will no doubt get the blame for Motherwell's defeat but the Steelmen did little to hellp themselves in a mediocre game which reflected the clubs positions in the bottom three places of the SPL.
Aberdeen at least created the platform for their matchwinning penalty with an incisive attack after six minutes which saw Laurent D'Jaffo bring the very best out of his fellow Frenchman Francois Dubourdeau with a sweetly struck left-foot volley.
From the corner David Partridge tugged Phil McGuire's jersey at the back post allowing Paul Sheerin to send the keeper the wrong way from the spot.
Unfortunately neither side drew inspiration from the early goal and a dismal spell was only briefly brightened by Shaun Fagen's deflected 20-yarder which failed to trouble keeper Peter Kjaer.
But the Dane was seriously tested just three minutes before the break when James McFadden fired in a swerving left-foot drive from long range.
Motherwell continued to press in the second half, but David Clarkson shot wide and then crossed for Pearson whose finish was smothered.
Having soaked up limited home pressure Aberdeen played cleverly on the counter-attack in the closing stages and only a desperate block from Steve Tosh's volley denied them a second goal.
Substitute Darren Mackie was also frustrated by a last-ditch tackle and there was still time for Motherwell to fall foul of those two crucial refereeing decisions.