Rangers defeated Hearts, while Dunfermline boosted their survival hopes.
Rangers came from a goal down to defeat Hearts, while Dunfermline boosted their hopes of avoiding relegation with victory over Dundee United.
Gavin Rae (52) and Barry Ferguson (79) turned the match around for The Gers after Andrius Velicka's 16th minute opener for the visitors.
Rangers' win means Celtic must wait until Sunday's trip to Kilmarnock before sealing a second successive SPL title.
Tam McManus, meanwhile, scored the 34th minute winner in Dunfermline's 1-0 win over Dundee United that lifted the hosts to within one point of second-from-bottom St Mirren.
Craig Dargo (14 & 45) scored twice as Inverness Caledonian Thistle defeated Motherwell 2-0.
Earlier in the day, Richard Foster's 35-yard shot 10 minutes from time rescued a point for Aberdeen in a 2-2 draw against nine-man Hibernian.
Damon Gray's right foot shot had given Hibs the lead in the 19th minute but parity was restored within six minutes courtesy of Russell Anderson's header from Barry Nicholson's corner.
The visitors regained the lead once more, though, when Dean Shiels pounced from six yards a minute before half-time.
Aberdeen missed a glorious chance to draw level three minutes after the restart after Darren Mackie's penalty was saved by goalkeeper Andrew McNeil.
Sean Lynch's professional foul on Chris Clark just four minutes later saw Hibs reduced to 10 men.
The visitors held out until the 80th minute when Foster's spectacular strike ensured a share of the spoils and Dermot McCaffrey also saw red for the visitors a minute from time.
Click below for an individual match summary:
Aberdeen 2-2 Hibernian
Dunfermline 1-0 Dundee United
Inverness Caledonian Thistle 2-0 Motherwell
Rangers 2-1 Hearts
