Livingston had their relegation confirmed after losing 1-0 at home to Inverness.
Barry Wilson scored the only goal of the game on 56 minutes to condemn Livi to the drop.
Rangers kept alive their hopes of finishing second in the table as they came from behind to beat Kilmarnock 3-1 at Rugby Park.
Colin Nish gave Killie a shock lead on 27 minutes, but Marvin Andrews drew Rangers level six minutes after the break.
Kris Boyd came back to haunt his old club to fire Rangers in front on 64 minutes and Andrews completed the comeback with his second of the game on 79 minutes.
Aberdeen moved into fifth spot with a thumping 4-0 win over Hibernian.
Stevie Crawford sent the home side on their way with the opener on 15 minutes and two goals from Steve Lovell (30, 54) put Aberdeen in control.
Richard Foster completed the rout with the fourth on 65 minutes to seal a miserable day for Hibs.
Falkirk continued their fine away form with a 2-0 win at Dundee United.
Alan Gow broke the deadlock on 14 minutes and Daniel McBreen doubled the lead on 39 minutes.
The only sour note for Falkirk was the sending off of Patrick Cregg late on.
Dunfermline beat Motherwell 3-2 after a five-goal thriller at Fir Park.
James Paterson gave Motherwell the lead after just seven minutes, but Iain Campbell equalised for Dunfermline on 21 minutes.
Mark Burchill fired Dunfermline in front when converting from the penalty spot on the half hour mark.
Gary Mason added a third on 50 minutes before Stephen Craigan set up a tense finish with Motherwell's second on 65 minutes, but Dunfermline held on for the win.
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