Thistle travelled to Kinross to face Portmoak in the search of another three points to keep their promotion aspirations alive.
Thistle should have opened the scoring inside the opening minute when McArthur found himself through on goal, but with only the keeper to beat he seemed to get the ball caught under his feet allowing Black to make the save.
After 41 minutes Thistle were made to rue several missed chances when the hosts took the lead after Paterson latched on to loose ball 30 yards out and struck a dipping shot which Henderson got a hand to but could not keep out.
With Thistle finding themselves behind at half time for only the second time this season, they knew they needed to up their game tenfold in the second half.
They did, and with just under an hour on the clock were back on level terms when Gorgon knocked a McLaren passinto the path of Gough who stooped to head the ball home at the back post.
Petrie had a glaring opportunity to put his side in front minutes later from an Ireland ball, but the big striker fired wide.
With only 13 minutes remaining Thistle were in front for the first time in the match when Shepherd did well to release Ireland who continued his rich vein of form slipping the ball under the advancing Black.
Substitute Ross almost made it 3-1 minutes after his introduction when he latched onto a driven ball from Ireland, but Black pulled off a great point blank save to deny him.
The deciding goal wasn’t to be far away when just a minute later Petrie finally managed to fire the ball into the net when he prodded home a Shepherd corner from close range.
Golf City Taxis Man of the Match – Liam Carson.
Thistle – Henderson, Brown, Carson, Gough, Provan (Munro 54 (Cameron 73)), Ireland, McArthur, McLaren, Shepherd, Gorgon (Ross 80), Petrie (Wanecki 86)
Sub – C. Murray
Tomorrow (Saturday) Thistle travel to Falkland to face Lomond Victoria in round two of the Peter Omand Cup with a 2.00pm kick off.