For all the recent exploits of Oldham and non-league Exeter City, this was the shock to spark the competition. Not since Coventry visited Anfield seven years ago have Liverpool been humbled at this stage.
Those purists who argue that the FA Cup's status has been damaged by understrength selections from clubs whose priorities are Premiership points will revel in the justice of it all. Burnley almost slipped into administration last year; today they awake thrilled by the most satisfying of victories and will relish a visit from Bournemouth, of League One, in the next round.
That Liverpool were beaten by a moment of utter madness merely added to the sense of occasion. Richard Chaplow - the game's outstanding performer, although his team-mate Jean-Louis Valois pushed him close - wriggled down the left wing six minutes into the second half and crossed optimistically into the centre.
Sami Hyypia slid in but failed to make contact only for Djimi Traoré, alone at the far post, to attempt a drag-back - a Cruyff-like turn, no less - in mid air. The loose ball dribbled off the instep of his left foot and into the empty net. It was as astonishing an own-goal as it was agonising for Liverpool, the home fans erupting in a mixture of delight and disbelief. "He knows it was a mistake," said the Reds manager Rafael Benítez. "He tried to control it with a man at his back but he should just have cleared it."
Traoré, visibly crestfallen, was substituted soon after but amid the odd battered shot from distance and the occasional nervous scrap in Burnley's area, Liverpool still departed the competition with a snarl. Antonio Nunez, remarkably a Real Madrid player six months ago, swung an elbow at Tony Grant and, for all that the midfielder crumpled eagerly, the Spaniard was shown a deserved red card.
That was a suitably ignominious reaction to mark a desperate occasion for Liverpool. Benitez's attempts to justify his selection will not have impressed the travelling fans, mortified by such a desolate display from their side.
The Premiership team were not only outfought but on too many occasions embarrassed too by gritty if unspectacular opponents. Steve Cotterill welcomed his Championship side's sixth consecutive clean sheet at home and spoke of "teamwork" and "industry" prevailing. That merely damned Liverpool further.
Alastair Campbell was whistling frantically in the stands as the seconds ticked down, though there was no need for his spin to embellish Burnley's performance. In Valois and Chaplow they had skill to complement their graft.
The Frenchman once delighted Luton Town, his extravagant skills helping to get them out of the old Third Division. He arrived at Turf Moor after inauspicious spells at Hearts and Clyde but now seems to have found his level.Hyypia alone appeared capable of dealing with his delivery.
His dribbles humiliated Igor Biscan, with Chaplow proving just as problematic on the opposite flank. The England Under-21 player's best moment came when he burst on to Valois' pass four minutes into the game, although the nervy Jerzy Dudek palmed his shot awkwardly away.
The pitch had been protected from snow flurries all day and, although Liverpool appeared suspicious of the turf, Chaplow revelled on it. Seemingly inspired by their young team-mate, Micah Hyde and Gary Cahill might also have scored when Burnley were on top in the first half.
Once their lead was established, moreover, Chaplow himself was denied at full stretch by Dudek, though he should have scored. "My heart was beating like a drum and my voice had gone," Cotterill added. "But we deserved it."
They did, if largely because Liverpool produced little of note, even after Milan Baros was introduced from the bench. Burnley travel to Cardiff on Saturday, albeit for a league game. Liverpool will not be visiting the Welsh capital on May 21.