Second-placed Aberdeen booked their place in the Europa League and maintained their nine-point lead over Rangers following a 2-1 win away at St Johnstone on Saturday.
Ryan Christie (19) put the Dons on their way to victory at McDiarmid Park and they doubled their advantage thanks to an own goal from Tam Scobbie (32).
Danny Swanson (48) pulled a goal back for fourth-placed St Johnstone, but it proved to be only a consolation.
Kenny Miller (39) and Jon Toral (54) were on target as Rangers defeated Partick 2-0 at Ibrox.
Inverness remain five points adrift at the bottom of the table after losing 4-2 away at fellow strugglers Motherwell.
Chris Cadden (7) and Louis Moult (9) put Motherwell firmly in control, but a double from Alex Fisher (21, 54) restored parity at Fir Park.
Motherwell regained their lead through Scott McDonald (65) and made sure of victory when Allan Campbell (70) notched his first goal for the club.
Dundee, who occupy the place immediately above Inverness, slumped to their seventh successive defeat after going down 2-0 at home to Hamilton.
Alejandro D'Acol (23) opened the scoring from the penalty spot and Michael Devlin (84) added a second to ensure Hamilton moved seven points clear of the relegation zone.