Motherwell missed the chance to move into second in the SPL after going down 3-0 at home to St Johnstone.
Stuart McCall's side would even have been level with leaders Rangers with victory at Fir Park, but they were denied by St Johnstone.
The visitors went ahead on 20-minutes with Tim Clancy putting through his own net, before second-half strikes from Francisco Sandaza and Liam Craig sealed an emphatic win.
In the day's early game, Hibernian climbed off the bottom of the table after drawing 2-2 at Dunfermline - but Colin Calderwood would have been left frustrated as they two-nil up.
Ivan Sproule and Garry O'Connor put Hibs ahead, but they could not hang on as Dunfermline levelled thanks to a Ryan Thomson strike and a Paul Hanlon own-goal.
Hearts are into the fourth after a 2-0 win over St Mirren at Tynecastle. Jamie Hamill opened the scoring from the penalty spot before Lee Mair put through his own net.
Inverness Caledonian Thistle dropped to the bottom of the table after going 3-1 at Dundee United.
Lauri Dalla Valle put United ahead early on, but Nick Ross levelled not long after for Terry Bucther's men.
But United emerged victorious with goals either side of the break from Danny Swanson and Jon Daly.
Finally, Aberdeen came from 2-0 down to claim a draw with Kilmarnock at Pittodrie.
Paul Heffernan and Dean Shiels put Killie two-up at the break, but goals from Andrew Considine and Youl Mawene secured a point for Craig Brown's side.