Rangers manager Mark Warburton savaged his side's shambolic display against Hearts after admitting it the worst of his Ibrox reign.
The Light Blues boss was left dumbstruck as Ian Cathro's relentless Jambos ran amok at Tynecastle in a devastating 4-1 win.
Gers could have been facing up to a repeat of September's five-goal Old Firm humiliation had it not been for keeper Wes Foderingham's late heroics.
And Warburton admitted his team only had themselves to blame.
The Englishman said: "We've just lost 4-1. We're Rangers Football Club, we don't lose 4-1. We did tonight and I feel frustrated, absolutely.
"We weren't good enough second half. On Saturday against Motherwell, I thought it was as good as we've played in 18 months.
"Tonight, second half was as bad as we've played in 18 months if not the worst."
Gers allowed Krystian Nowak to head the hosts ahead after just four minutes and while Emerson Hyndman - the only outfielder in blue to get pass marks - volleyed them level after 36 minutes, the Glasgow side fell apart after the break.
Jamie Walker smashed home Hearts' second after Andy Halliday's slip four minutes into the second period before grabbing another after Don Cowie had tapped home the third.
Warburton - whose side also lost on their last visit to Gorgie back in November - added: "To give away four minutes into the second half is just ludicrous. We win together and we lose together but that was way below the levels of Rangers Football Club.
"I didn't see it coming. Nobody did, the players or staff. We all have bad days at the office, like last time we were here, but we thought we had learned from the first visit not to give the crowd anything.
"But we gave away schoolboys errors at the start of each half. We have to be better than that.
"To give away those type of goals was unacceptable."
The travelling Gers support laid into their team at full-time and also took aim at Warburton when he replaced on-loan Bournemouth youngster Hyndman with half an hour left.
But the boss said: "He is 20 years old, hasn't played many 90 minutes and on Saturday he played an outstanding 90 minutes. He is a young, precocious talent and Saturday took a lot out of him.
"The pitch out there is so heavy. We've got a responsibility to his parent club. We have got to look after their asset."
The victory was a huge boost for Cathro as he claimed just his third win since replacing Robbie Neilson.
His side - boosted by the tireless workrate added by new striker Isma Goncalves - never gave Gers a minute's peace.
The Gorgie boss said: "I'm pleased that a lot of people have been able to let out some of the frustrations they've been through in the more difficult moments we've experienced so far.
"What impressed me most about the performance was that it lasted for 90 minutes. That's important.
"Isma offers that tenacity, he attacks directly. He doesn't wait around, he goes and makes things happen. That's what we wanted in the squad. It was nice for him."
And the rookie head coach admitted the win soothed some of the frustrations suffered during his testing opening two months as boss.
"Sometimes it hurts, you know," he admitted. "We stay strong together and none of the noise gets in. But sometimes you still suffer.
"I enjoyed seeing the players enjoying themselves, letting it all out. So it's out now. And we move on."