Does Spurs' win at Old Trafford mean Manchester United's title challenge is over, and what effect has Tim Sherwood had?
• Read Daniel Taylor's match report here
After Arsenal, Manchester City, Chelsea and Liverpool all won earlier on New Year's Day the champions started this one 11 points behind Tottenham meaning a win was imperative to maintain any kind of challenge.
During the buildup David Moyes had insisted: "We're still in it." After this defeat – a fourth in the league already at home – the manager may cling to the mantra but the truth is that qualifying for the Champions League is now the big challenge.
Reflecting on a first six months in charge Moyes also said: "It would have been a hard job at United for anybody and it's been a hard job for me." What will also prove very tricky is strengthening this month, which is what Moyes needs to do to have the best chance of leading the club to fourth position, at least.
The evidence of the failures at first Chelsea then Tottenham Hotspur showed that André Villas-Boas has a deficit in the art of man-management, the asset most required in an age of millionaire players.
These are early days in Tim Sherwood's tenure, though to witness Emmanuel Adebayor tussling with Wayne Rooney near his own corner flag towards the end of the first half was to view a prime illustration of how Villas-Boas's replacement is motivating the same group. Since Sherwood reintroduced Adebayor as a starting striker he has scored four times, the last of which was the opener here: the way he rose majestically then placed the header to the left of David de Gea oozed class and indicated Sherwood can spot – and inspire – a player.
Having been left out of the previous five match-day squads Rio Ferdinand did find himself in this one as he was named a substitute. The dimming of the light on the 35-year-old's career has opened a vacancy for one of Jonny Evans and Chris Smalling to shine and finally establish themselves as a first choice. Yet the way they were sliced through for Adebayor's finish will concern Moyes, with Smalling in particular unable to deal with the delivery that created it.
After the box-to-box sequence of slick passing that took in Kyle Walker, Christian Eriksen, Roberto Soldado and Eriksen again that gave Spurs the lead the visitors should have been two up almost instantly. Again, United were splayed too easily, this time by the pace of Aaron Lennon whose raking delivery had the defence flat-footed only for Soldado to miss from close in.
Before kick-off Sherwood said: "We'd like Wayne Rooney to be still injured, to be honest, but he's not so we just have to get on with it. We have players who can hurt them."
Into this category fell the Belgian central midfielder whose barracking performance, especially before the break, recalled his display in the visitor's 3-2 win here at the start of last season.
Then he bossed the game, allowing Spurs to take the contest to United and, while on Wednesday Dembélé's impact was not as great, he again showed up the glaring hole in Moyes's midfield resources.
The Belgian continually picked up Rooney whenever the forward dropped deep to outmuscle and frustrate United's totem. This drew a booking for him during the opening stanza and, when the Liverpudlian was deployed permanently alongside Tom Cleverley, it was Dembélé who once again stifled him expertly.
"Now at Old Trafford we need to start making home advantage count. Manchester United are traditionally very strong at home and I am confident that we will put that right over the course of the remaining games we have at Old Trafford this year."
These pre-match words from Moyes proved wishful thinking as the defeats to Newcastle United and Everton at the start of December were repeated in a reverse in which United started well and proceeded to get poorer and poorer.
The sense that the Old Trafford factor is fading was strengthened when Howard Webb turned down two second-half penalty appeals as Danny Welbeck and Ashley Young took a tumble: despite the fury that met Webb following the latter of these the official was unmoved. In the not so distant past of United's dominance he may have awarded at least one of them.