Donegal Celtic's 2-1 home win over Dungannon Swifts means they cannot finish bottom of the Irish Premiership.
Mark Burns headed DC's opener in the 11th minute after Dungannon keeper Tuda Murphy had failed to cut out Kevin Keegan's corner.
The west Belfast men made it 2-0 in the 37th minute as Ryan Deans did well to keep the ball in before crossing for Kevin Hughes to head in.
Dungannon's 51st-minute score was an own goal by DC defender Pat McShane.
It came after a goalmouth scramble when Matt Hazley had delivered a corner into the danger area.
Dungannon pressed for an equaliser and a low PJ Lavery free-kick had keeper John Connolly scrambling across his goal.
Connolly then made a good save from Dungannon defender Adam McMinn.
"There was a lot of tension at the end and we were holding on a bit but I think we probably edged it," said Celtic manager Packie McAllister.
"We may have to face a play-off but for now I am relieved.
"I am pleased with the way things have gone recently - the lads have done well."