Leeds United fell to back-to-back defeats for the first time this season as Nottingham Forest ran out 4-2 winners over Marcelo Bielsa's men on a frantic afternoon at the City Ground.
Despite a second defeat in four days – Leeds were beaten 2-0 at home by in-form Hull City on Saturday – the West Yorkshire club remain top of the Championship standings by two points, after second-placed Norwich City were held to a 1-1 draw at Brentford.
Marcelo Bielsa named an unchanged line-up once again for the New Year's Day showdown at the City Ground as Pablo Hernandez made his 100th appearance for the club.
Forest were without the Championship's top goalscorer as Lewis Grabban missed out with a knock meaning Daryl Murphy stepped into the team in his place.
It was the Irishman who has the first attempt as goal in the early stages as the ball fell nicely for him outside of the area but his volley flew past the post.
Both sides settled into the game well but it was a mistake that handed the visitors the lead after just six minutes.
An aimless ball over the top was swept up by Adam Forshaw but the midfielder under hit his pass back to Bailey Peacock-Farrell which allowed Jack Colback to pounce and round the Leeds stopper to tap home into an empty net.
The visitors again threatened as Danny Fox hit the post with a header from a corner as the home crowd roared on their side.
There was to be a moment of controversy that followed as Barry Douglas played a ball over the top which Jack Harrison latched onto with the Forest defence asleep.
The City loanee collected the loose ball but was brought down by defender Jack Robinson with the winger about to shoot.
United's players were pleading for a red card but referee Darren England brandished the yellow despite the protests.
Leeds were spurred on by the decision as they went close twice through Gjanni Alioski as he headed a Pablo Hernandez cross over the bar before Forest's Joe Lolley flicked away another headed chance from a corner.
Just as the Whites were on top Bielsa's men were themselves down to 10 men as Kalvin Phillips was given his marching orders.
A heavy touch allowed substitute Adlene Guedioura to collect the ball as Phillips lunged in with England this time pulling out his red card.
Forest had another glorious opportunity to add to the scoreline before the break as another loose pass from Forshaw allowed Lolley through on goal but Peacock-Farrell this time came to his rescue to nab the ball from the attacker's feet.
United super sub Jack Clarke was introduced at the break once again in place of Jack Harrison as Bielsa opted for three at the back following the dismissal.
Hernandez fired the first warning shot from Leeds who were having to take a lot of risks to open up Forest with the hosts playing very much on the counter attack.
Leeds though didn't have to wait long to be level as Mateusz Klich drove forward from midfield to pick out the run of Clarke on the right who slotted home underneath Costel Pantilimon to level up proceedings.
United had another glorious opportunity to add to the scoreline as Luke Ayling played a ball over the top for Kemar Roofe.
The Whites striker gathered as Pantilimon rushed out of his goal in an attempt to clear but his lifted effort fell agonisingly the wrong side of the post.
It wouldn't take long though for Leeds to grab the lead they deserved.
A corner made it's way back out to Hernandez who swung in a inch perfect ball for Pontus Jansson at the back post who nodded the delivery back across goal for Alioski to emphatically smash home and sent the visiting fans delirious.
Forest pegged the visitors back just five minutes later as Colback struck once again with a tidy finish from inside the box as Leeds failed to deal with a corner.
It was another set-piece that handed the hosts the advantage three minutes after the leveller as Murphy headed home at the back post from a corner.
Aitor Karanka's side added a fourth through substitute Ben Osborn as he all but sealed the points to complete a frantic 11 minutes of action.
The forward latched onto a ball from Murphy and cut inside the area to rifle home a curling effort off the underside of the crossbar.
Leeds went close through Roofe as he found himself one-on-one with Pantilimon before heading over the bar in injury time.
United failed to muster another improbable comeback as Bielsa was handed back-to-back defeats for the first time this season to start 2019 with a defeat.
Nottingham Forest: Pantilimon, Darikwa, Hefele, Fox, Robinson, Yacob, Colback, Cash, Carvalho, Lolley, Murphy. Subs: Steele, Guedioura, Osborn, Janko, Yates, Dias, Appiah
Leeds United: Peacock-Farrell, Ayling, Jansson, Phillips, Douglas, Forshaw, Alioski, Klich, Hernandez, Harrison, Roofe. Subs: Huffer, Halme, Clarke, Davis, Shackleton, Baker, Roberts.