Partick Thistle secured the final promotion play-off spot and extinguished any hopes of Livingston's Scottish Championship title party with a narrow win in West Lothian.
It was an own goal by Heart of Midlothian loanee midfielder Macaulay Tait that gave the Jags the deciding goal seven minutes before half-time.
There was a nervousness emanating from the stands with a lot at stake for both sets of supporters and that was definitely finding its way on to the pitch.
As early as the third minute, player-manager Brian Graham was gifted a chance to give Thistle the lead but blasted over from 12 yards with the goal gaping.
At the other end, Robbie Muirhead was clean through on goal after a terrific flick-on by Cristian Montano, but goalkeeper David Mitchell stuck out his left boot to deny the Livingston striker.
The home side continued to dominate but were hit by a sucker-punch seven minutes before the break.
Kanayo Megwa fired a cross into the Livingston box that Tait attempted to clear but could only knock the ball beyond his own goalkeeper high into the net.
Livingston kept driving forward and Stephen Kelly's effort rebounded off the underside of the crossbar and clear.
As news filtered through of Falkirk leading Hamilton Accies, the home fans' hopes of a title party were becoming slim.
However, the team kept pushing forward and Lewis Smith had a goalbound effort blocked by McBeth as they laid siege on the Thistle goal.
Thistle now face Ayr United on Tuesday at Firhill, with the second leg of their quarter-final a week later at Somerset Park.
Livingston await the winners for the right to face whoever finishes in second bottom spot in the Premiership for a place in next season's top flight.