IAN McCall's side's hopes of promotion received a severe dent when a surreal own goal gifted all three points to relegation-threatened Clyde.
Both sides started tentatively and it wasn't until the 14th minute that the spectators had some goal-mouth action to distract their attention from the icy wind which enveloped Firhill. Marc Twaddle's low cross ought to have been cleared by the Clyde
rearguard but the ball was allowed to travel to Gary Harkins and his left-foot snapshot was parried by David Hutton.
Kris Doolan also came close for the Jags midway through the first half but unfortunately for the striker, his chip from 12 yards landed on top of the net.
Clyde defended obdurately, though, and there was further frustration for the home side when Simon Donnelly shot into the side-netting and then Hutton managed to beat away the latter's angled drive from point-blank range.
It was all Thistle, then, which made it all the more surprising when Clyde took the lead in bizarre fashion.
There seemed little danger when Ian Maxwell rolled the ball back to goalkeeper Jonny Tuffey but the Northern Ireland internationalist took his eye off the ball as he swung at it and it bobbled over his foot and behind him, crossing the goal-line before he could rectify his error.
Thistle claimed a penalty when Mark Brown sent Donnelly sprawling but referee Mike Tumilty awarded a corner instead and Hutton then produced a superb reflex save to push over Paul Paton's piledriver and safeguard the points.
