Matt Mills struck the only goal as Championship Reading claimed another notable scalp to reach the FA Cup quarter-finals for a second successive year.
Mills fired home after 26 minutes of tonight's fifth-round tie at Everton to put the Royals, who knocked out Liverpool en route to the last eight in 2010, within a game of Wembley.
Jimmy Kebe should have made victory more comfortable but goalkeeper Alex McCarthy also proved a hero with a stunning late save from Leon Osman.
Everton supporters booed at the final whistle and left Goodison Park frustrated as the inconsistency which has dogged their campaign returned to haunt them.
Their memorable fourth-round success at Chelsea, it appeared, had proved another false dawn.
The Toffees lacked a cutting edge in the first half and the situation was not helped by the late arrival of their weekend goal hero Jermaine Beckford.
Beckford, who struck twice against Sunderland on Saturday, was held up in traffic on the M62 in the afternoon and could only make the bench.
That left Louis Saha, who had his own car trouble when he crashed his Ferrari on Sunday, up front alone ahead of a midfield lacking influential duo Marouane Fellaini and Tim Cahill through injury.
Reading got behind the Everton defence in the first minute but Kebe's cross went behind Shane Long and the in-form Royals striker could only flick tamely at goal.
Everton soon began to assert themselves and won a free-kick which Leighton Baines swung into the box dangerously. Mikele Leigertwood headed behind for a corner under pressure from Rodwell.
Baines and Diniyar Bilyaletdinov then combined well for Osman to send over a teasing cross to the far post for Seamus Coleman but the Irishman headed into the ground and the ball agonisingly bounced over.
Osman tested McCarthy with a powerful left-foot shot from the edge of the box but the goalkeeper, deputising for the injured Adam Federici, saved comfortably.
Long had another chance for Reading when he was picked out by a deep Ian Harte cross but Tim Howard easily claimed his header.
Reading, having been starved of possession for a spell, took encouragement from that and made what they had of the ball count as they claimed the lead from a 26th-minute corner.
Osman blocked as Mills met Harte's cross with a header towards goal but the Everton midfielder could only poke back to the Reading man as he attempted to clear.
Mills skilfully took the ball on his chest and then slammed a low shot past Howard.
Everton were shocked by the turn of events and should have gone another goal behind moments later.
A mistake by Sylvain Distin allowed Kebe a clear run on goal from 40 yards but Howard was alert and stood up well to block the Mali international's shot.
Osman went close to an equaliser just before the break when he headed over from a Baines corner.
Everton boss David Moyes felt the need to freshen up his attack at the interval and sent on Beckford and Victor Anichebe for Bilyaletdinov and Coleman.
The Toffees immediately looked more threatening and pieced together a move which led to Saha setting up Beckford but the former Leeds striker shot straight at McCarthy.
A shooting opportunity opened up for Mikel Arteta from distance as Everton came forward again but the Spaniard fired wide from distance.
Yet just as Everton supporters might have started to sense a fightback, Reading served another warning of their potency as veteran Harte flashed a 30-yard free-kick narrowly wide.
The Toffees applied more pressure but Saha and Jack Rodwell both had efforts blocked as the hosts started to get frustrated.
Everton had another major let-off 15 minutes from time when Jay Tabb found space in the penalty area but had a firm shot deflected behind.
The Merseysiders' next opportunity came from a corner of their own as McCarthy failed to punch clear.
Saha pounced on the loose ball and turned to shoot but Beckford inadvertently blocked and the Royals survived.
McCarthy proved his ability moments later, however, with a stunning save from Osman.
Osman looked certain to score as he met a Beckford nod-down with a sweet volley but McCarthy somehow palmed the ball over from point-blank range.
Everton appealed for a penalty when the ball appeared to brush Harte's arm but referee Andre Marriner was unconvinced.
Everton pressed on throughout five minutes of injury time but Reading held on.