Aberdeen missed the chance to move above Hibernian and into fourth spot in the Scottish Premier League after drawing 2-2 with Dundee United on Wednesday.
An early strike from Scott Vernon handed the home side the lead, but a header from Gavin Gunning and a Jamie Langfield own goal moved Dundee into the lead.
Aberdeen were level moments into the second period when Niall McGinn pounced to score from close range, but neither side could add a winner in the final stages.
Meanwhile, Kilmarnock passed up the opportunity to move level on points with sixth-placed St Johnstone after sharing the points in a 1-1 draw with St Mirren.
Kilmarnock were ahead inside five minutes when Liam Kelly converted from the penalty spot, but a penalty from Paul McGowan 20 minutes from time secured a share of the spoils for St Mirren.
Results in full: St Johnstone 1-0 Dundee, Aberdeen 2-2 Dundee United, Celtic 1-0 Motherwell, St Mirren 1-1 Kilmarnock
