Manager Alan Archibald was furious with Partick Thistle's defending as they crashed to a 4-1 loss at home to Inverness Caley Thistle.
The out-of-sorts Jags lost to the Highlanders for the first time this season and are not yet clear of the relegation play-off place.
"I've not seen us defend like that for a year and a half," Archibald told BBC Scotland.
"The second half was not acceptable; it was miles away from where we've been."
Partick showed spirit in the opening 20 minutes but thereafter struggled to create opportunities or keep it tight at the back.
"We'll watch it back and go over it because we've built our success on being hard to beat and not giving anything away," said Archibald.
"If it wasn't for [goalkeeper] Ryan Scully it would have been more.
"I felt sorry for young Ryan because believe it or not, he's played well and we've lost 4-1. We'll be back to work to make sure we put this right."
Partick Thistle are six points in front of 11th placed Kilmarnock with nine to play for and visit Rugby Park next Saturday.
"It's in our own hands," added Archibald. "We need to get that victory and if they don't it puts pressure on you.
"We said to them after the game that people like the hysteria of more teams getting dragged into it. We're in a good position but with performances like that we put a lot more pressure on ourselves.
"I've been here before. I never said we were safe and I know we need to get over the line."
Inverness Caledonian Thistle boss John Hughes was delighted that goals from Carl Tremarco, Miles Storey, Josh Meekings and Jordan Roberts ended a bad run against the Maryhill side.
"To come here and win 4-1 knowing that Partick are a bit of a bogey team for us; all credit to the boys," he told BBC Scotland.
"To be honest it could have been more. I was looking for another two or three.
"Carl should be well up to eight or nine goals this year because he gets in on that back post and he just needs to learn how to finish.
"The way we play the game, I'm all for one full-back crossing it and the other full-back putting it in at the back post. I don't usually single players out but him and Ross Draper were absolutely outstanding.
"Ross really drove the team forward, winning tackles and on the front foot and showing a spirit and determination that the rest of them just followed."
Richie Foran came on as a second half substitute for Caley Thistle to set up Roberts' goal and his manager reckons the forward can be like a new signing for next season if he stays in good condition following an injury-blighted last two years.
"Six months ago you're saying to yourself 'Richie I just can't see you getting there', it was one thing after another," said Hughes.
"But in the last couple of months he's training every day, getting himself fitter and fitter and starting to look like the old Richie Foran.
"Fingers crossed, he can stay injury free and get that pre-season in him that he'll need and then I think he's got a part to play next season."