Two 2nd half goals saw Celtic win 2-0 at home to St Mirren. Elyounoussi netted in the 49th minute before Forrest celebrated his new contract by doubling the Hoops' advantage.
Steven Gerrard celebrated his 50th Rangers match with a 4-0 away win against Ross County. Ryan Jack and Alfredo Morelos got 2 goals each for the Gers.
Elsewhere, Motherwell leapfrogged Kilmarnock by winning 1-0, Hibs came from behind to draw 2-2 with Livingston, Aberdeen won 1-0 away to Hamilton, and St Johnstone piled more misery on Hearts by winning 1-0.
It all means that Celtic are still top of the table, albeit by 1 goal.