Linfield 1-0 Cliftonville
Linfield are virtually assured of their 50th Irish League title thanks to Peter Thompson's 56th-minute winner at Windsor Park.
The victory leaves the Blues six points ahead of second-placed Crusaders and they have a better goal difference by 24 with just two matches left.
Striker Thompson, playing his 300th match for Linfield, pounced on a loose ball after a corner for the goal.
It keeps Linfield on course for a fifth double in six seasons.
They face Crusaders in the Irish Cup final on 7 May.
When confirmed, it will be David Jeffrey's eighth championship triumph as manager of the Belfast club and his 27th trophy overall.
Linfield could have taken the lead in the first half but Cliftonville keeper Jack Duffin did well to save from Paul Munster and also to fingertip a Michael Carvill shot behind for a corner.
However, the best chance of the half fell to the visitors shortly before the break when Conal Burns blazed wide from a great position in the penalty area.
After the goal, Philip Lowry had an overhead effort cleared off the line by Aaron Smyth and Carvill saw his low shot turned behind by Duffin for a corner.