Sheffield Wednesday were brought plummeting back down to Earth with an almighty thud by bogey side Middlesbrough.
Second half strikes by Mo Besic and Britt Assombalonga condemned Jos Luhukay's men to a first Championship defeat in five outings.
In-form midfielder Adam Reach reduced the Owls arrears in the 82nd minute, finding the back of the net for a third time in four matches, to set up a grand-stand finish.
But it proved too little too late as Boro deservedly clinched maximum points to go top of the pile.
In truth, Wednesday did not merit a point, although they laid seige to the Teesiders goal late on.
Reach twice came agonisingly close to putting them ahead in an even opening 45 minutes but Boro outclassed them for long periods in the second half.
The result should act as a reality check and a stark reminder that the Owls remain a work in progress.
After a cagey start, Wednesday created the first meaningful opportunity in the 12th minute.
Barry Bannan dispossessed former England international Stewart Downing just inside Boro's half and the Scotland international played a lovely one-two with Steven Fletcher before dinking in a delightful cross but man of the moment Adam Reach saw his glancing header clip the top of the crossbar.
Boro, play-off semi-finalists last season, have built their success on a miserly defence so far. They entered the contest, having chalked up eight clean sheets in 12 outings.
Tony Pulis teams are renowned for being physical and strong from set pieces and a long, booming throw in from Ryan Shotton caused panic in the Owls defence, with Cameron Dawson spilling the ball inside the six yard box but the hosts snuffed out the threat.
Downing was a real nuisance on the right flank with his nimbleand he also showed his dead ball prowess in the 26th minute. His teasing free-kick was nodded wide by Daniel Ayala but referee Peter Bankes awarded a corner.
Wednesday were sloppy at times in possession. Their passing was erratic and they lacked cohesion in the final third.
Nonetheless, Reach, lining up against his former club, almost scored another stunner before the half hour mark. The 25-year-old, who kicked off his career at Boro, caught George Friend napping at the back before bursting forward and unleashing a fierce right foot effort which flew inches over the top. TV replays clearly showed Darren Randolph saved Reach's effort but Bankes signalled for a goal kick.
Hector, on loan from Chelsea until the end of the campaign, continued his excellent form. The centre-back has barely put a foot wrong since moving to Hillsborough and he expertly threw himself at a stinging Adam Clayton 20 yard shot as Boro briefly threatened to break the deadlock. It was a brave piece of defending, epitomising Hector's commitment to the cause.
It was far from a classic contest. Both sides cancelled each other out. It was easy to see why Middlesbrough boast the meanest defence in the division.
But the visitors were predictable and short on quality at the business end of the pitch. They registered just one shot on target in a dull first half, Mo Besic's tame left foot drive was comfortably kept out by Dawson.
Whatever Pulis said to his players at half-time worked a treat as Borok took complete control after the break.
Besic handed them a 49th minute lead following lovely approach play involving the lively Downing and Howson. The Bosnian midfielder cut the ball onto his right foot and drilled the ball across Dawson into the far corner.
Besic's strike knocked the stuffing out of Wednesday, with Howson testing the reflexes of Dawson.
Besic turned provider for Boro's second. He intercepted a woeful back pass by captain Tom Lees, sprinting through on goal before unselfishly squaring to Britt Assombalonga, who stayed onside and had the simple task of tapping home into an unguarded net. It was an uncharacteristic mistake by Lees which left the Owls chasing the game.
Boro must have been thinking Christmas had come early.
Moments later, Besic's decision-making let him down. He should have slipped in Assombalonga, who was in acres of space after a rapid counter attack by the visitors, but he went for glory and Dawson and was equal to it.
Lucas Joao, one of two changes to the starting line-up by Luhukay, was quiet and struggled to make an in impact so it was no surprise when he was withdrawn just after the hour mark.
Atdhe Nuhiu, Joao's replacement, nearly made an instant impact. His downward header from Reach's cross was hacked away from near the goal line by Aden Flint, who was immense for Boro.
Reach gave the Owls a lifeline, superbly volleying home with his 'weaker' right foot after the visitors had only partially cleared a Bannan centre.
Wednesday, attacking the Kop end, piled on the pressure in the dying embers of a bizarre second half.
Five minutes of time was added on and Boro somehow survived a major goalmouth scramble, with Ayala diving on the goalline to prevent Lees from turning the ball in from close range.
Has the Owls bubble burst? Not necessarily but Luhukay will be disappointed with their ragged, disjointed display as they suffered their first home league defeat of the season.
They paid the price for sloppy defensive mistakes. The search for a clean sheet continues and defeat means Wednesday have failed to win any of their last six meetings with Boro.
Owls: Dawson; Lees, Hector Thorniley; Palmer, Pelupessy, Bannan, Penney; Reach, Joao (Nuhiu 63), Fletcher. Substitutes: Wildsmith, Fox, Pudil, Onomah, Kirby, Preston.
Middlesbrough: Randolph; Ayala, Flint, Fry; Shotton, Clayton, Besic (Batth 90), Howson, Friend; Downing (Saville 85), Assombalonga (Hugill 78). Substitutes: Lonergan, McQueen, McNair, Gestede.
Referee: Peter Bankes (Merseyside)
Star man: Michael Hector