The Clarets' proud unbeaten home record was punctured by old foes Reading on an afternoon of torment at Turf Moor.
Reading's last visit 18 months ago had ended in defeat in the Championship play-offs on an afternoon which saw Andre Bikey take an early bath.
This time Bikey was in a claret and blue shirt and it was his defensive partner Leon Cort who failed to see out the 90 minutes as Reading ruthlessly exposed Burnley's ten men to hand the Clarets a first defeat in eight games.
Cort was dismissed for a second yellow card following an earlier caution which handed Reading the opening goal from the penalty spot after just eight minutes.
And things never got better from then on for the Clarets on a collective bad day at the office.
Burnley never clicked going forward and saw their previously water-tight defence breached for only the second occasion at Turf Moor this season as Reading produced an almost copy-book away performance.
The Royals doubled their lead 19 minutes into the second half through Jobi McAnuff and then - as the under-manned Clarets chased the game late on - struck twice more in the last few minutes through substitute Michail Antonio and Simon Church.
Leon Cort collects his second yellow card.....
....and makes his way for an early bath
Their efforts sent the Clarets down to seventh in the table and needing to re-group ahead of Wednesday's Carling Cup clash at Aston Villa and next Saturday's trip to Championship leaders QPR, following a performance boss Brian Laws will hope was only a temporary blip.
Strangely, given the way they had finished in their mid-week win over Barnsley - their fifth in six attempts at Turf Moor - the Clarets started sluggishly as they handed Reading the initiative.
Jay Tabb's return from injury gave the Royals some extra vibrancy in midfield and he had already seen a shot blocked by Cort when he had a hand in the opening goal.
Tabb's ball from midfield released Shane Long who out-paced Cort to reach the penalty area, where Cort's desperate tackle brought a spot-kick and a first booking in a league fixture for over six years.
Long duly beat Brian Jensen low down to his right and with the Clarets knocked out of their stride, the response was minimal.
Flooding the midfield and allowing Burnley's play-makers not time on the ball, Reading looked comfortable with their lead and had a couple of efforts at doubling it as Long fired into the side-netting and McAnuff forced Jensen to save his long-range effort.
Burnley's usual potency at home deserted them with chances few and far between.
An excellent cross from Wade Elliott just evaded Chris Iwelumo and the big striker then headed a Chris Eagles free-kick just over the top.
Chris Iwelumo strives to get Burnley level
The Clarets' had a penalty appeal turned down when Iwelumo was bundled over by Matt Mills - but Adam Federici's only save before the break was a scrambling effort to keep out a deflected shot from Rodriguez that lacked the power to beat the Reading keeper.
Laws resisted the opportunity to change things at half-time, but whatever he said at least seemed to have some effect as the Clarets showed greater urgency and more of a threat at the start of the second half.
Eagles came alive and stung the palms of Federici before sending a flying volley wide of the target when Tyrone Mears returned the loose ball.
Eagles then released Rodriguez for a run and shot which was blocked into the path of Eagles, who scuffed an effort wide.
But just when the Clarets sensed they might force a way back into the game Reading struck to make it 2-0 after 64 minutes.
Jay Rodriguez strives to get the Clarets going
A free-kick from Ian Harte was headed half-clear by Danny Fox but only into the path of McAnuff, who calmly steered a shot in off the inside of a post from 12 yards.
And things got worse three minutes later when the Clarets were reduced to ten men.
Having avoided the referee's notebook for so long, Cort picked up a second yellow card for a foul on Long to become the fourth Burnley player to sent off this season.
The defender's dismissal summed up a disappointing day, which would have got worse but for Jensen, who made two fine saves in a matter of moments with 20 minutes to go as he dived at the feet of Long and then tipped a McAnuff shot round the post.
Laws sent on Steven Thompson and Martin Paterson, goal-scoring hero of the play-off semi-final two years ago, to try and inspire a late fightback.
Brian Laws makes a point to the officials
And the pair helped liven things up as Burnley finally put some pressure on the Reading goalmouth, with fellow substitute Ross Wallace sending in some typically teasing crosses and then cracking a volley just wide.
Inevitably there were gaps at the back though, and after a number of near misses Reading finally put the seal on a second away win as the impressive Long crossed for Antonio to tap in at the far post.
Reading then added a fourth in stoppage time when Church sliced an effort into the top corner to hand the Clarets their first home defeat in the Championship since February, 2009.
Burnley: Jensen, Mears, Fox, Cort, Bikey, Cork, Marney (Wallace 65), Elliott, Iwelumo (Paterson 75), Rodriguez (Thompson 75), Eagles. Subs: Alexander, Duff, Easton, Grant.
Reading: Federici, Griffin, Khizanishvili, Mills, Robson-Kanu, Karacan (Church 75), Tabb (Antonio 82), McAnuff, Long, Howard, Harte. Subs: Hunt, Cummings, Pearce, McCarthy.
Referee: Nigel Miller.
Booked: Burnley: Cort 7, 67, Elliott 40, Cork 85
Sent off: Cort
Reading: McAnuff 66
One of those days