Partick are in danger of being sucked back into the play-off scrap after a shambolic display saw them crash to a 4-1 Firhill defeat against Inverness.
Alan Archibald's team were booed off at the end of both halves as they allowed 11th-placed Kilmarnock to pull within six points.
Inverness - who had not won any of their last six meetings with the Maryhill outfit - made the most of Thistle's dreadful defending to grab the win which guarantees their safety as Carl Tremarco, Miles Storey, Josh Meekings and Jordan Roberts all netted.
Jags striker Kris Doolan pulled one back while his side were three down but there is now real concern amongst the Partick faithful that they could end up in trouble.
They face Killie at Rugby Park next weekend and defeat would leave them sweating on their top-flight safety.
Yet the hosts started brightly enough, with Steven Lawless dragging a shot wide inside the opening three minutes.
But it all went wrong when the visitors struck first after 14 minutes.
Roberts launched a long clearance up to halfway, picking out Andrea Mbuyi-Mutombo. The impressive Belgian knocked a first-time pass out for Tremarco and there was no catching the left-back as he surged 40 yards upfield before clipping a tidy finish in off the post.
Sean Welsh curled a decent free-kick over the Inverness wall as Partick went in search of a leveller but was denied by keeper Owain Fon Williams.
And Partick were unpicked again just a minute into the second period.
Mbuyi-Mutombo was the instigator once more as he nudged a loose ball over the top of the Jags defence for Storey to run onto.
The home defence were quick to claim for offside but the on-loan Swindon striker did not wait as he smashed at goal. The ball appeared to be heading wide but Thistle keeper Ryan Scully's touch inadvertently altered its course onto the the woodwork as it bounced in.
Mbuyi-Mutombo's bustling leg work almost paid off again he barged into the box but the former Postmouth trainee could only find the side netting. The 25-year-old then swept a delicious cross to the back post but Roberts' shot came back off the post before Scully pounced on the loose ball.
Inverness were firmly in control by that point but Storey wasted a decent chance when he volleyed over just eight yards out, while Roberts also fired wide as Partick's defence opened up again.
Partick defender Dan Seabourne then had to dart back and boot clear as Mbuyi-Mutombo's power again cause havoc in the box but Inverness did net again as Josh Meekings was left totally unmarked to volley home from Greg Tansey's corner with 14 minutes left.
Doolan grabbed a consolation effort seven minutes from time as he slotted home after Fon Williams fumbled but Inverness ran straight up the park and added their fourth as Roberts finished off good work from substitute Richie Foran.
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