City still hold the advantage on goal difference, but even that lead was cut to five by United's second successive five-goal triumph.
It was tough luck on Wigan, whose chance disappeared once Conor Sammon was sent off for catching Michael Carrick with his elbow just before the break.
Already leading through Park Ji-sung's early goal, United took maximum advantage.
Berbatov doubled their lead before half-time, then scored twice more, bringing back memories of his form in the first half of last season, when he claimed three match balls.
On this occasion, he owed the honour to Wayne Rooney, who stepped aside to let him take the penalty after Park had been fouled by Antolin Alcaraz.
The excellent Antonio Valencia was also on target to ensure Sir Alex Ferguson will be handed the perfect 70th birthday present of a place on top of the table should his side overcome Blackburn on New Year's Eve, given City are not in action until 24 hours later.
If there was one game where Ferguson might not have been too alarmed to field a defence including Michael Carrick and Antonio Valencia, this was it.
Wigan had not managed so much as a draw in 13 previous meetings between the sides and the combined score from their past four encounters was 16-0.
United soon added to their tally as Patrice Evra slalomed his way into the Wigan box, then picked out Park Ji-sung with a neat cut-back.
The South Korean had enough space to pick his spot, into the top right corner, well out of Ali Al Habsi's reach.
United continued to create chances at regular intervals, with Nani, Berbatov and Darron Gibson all trying their luck.
However, Wigan were not content to play the meek visitors and with Victor Moses building on recent impressive performances and Ronnie Stam exploiting the hosts' lack of an orthodox left-sided midfield player, created just as many chances as their hosts early on.
Sammon wasted the best, turning onto David Jones' pass but drilling a shot straight at Anders Lindegaard.
The Irishman's day quickly got much worse, and any chance Wigan had disappeared.
There is no doubt Sammon's arm did end up in Carrick's face, offering referee Phil Dowd the opportunity to send him off.
However, it did appear the Wigan man was attempting to use it as a barrier to shield a bouncing ball from his opponent.
There was no malice, and very little force, behind the action and Latics chief Roberto Martinez was not on his own in believing his side had been harshly treated.
And, as good sides do, United quickly exploited the situation.
Had injury not struck him down in August, Gibson might well have moved on in the summer.
As it was, Ferguson was probably glad to have him available for this one.
The Irishman delivered a teasing cross from the right flank, which ended up with Berbatov.
Making only his second Premier League start of the season, United's record signing took some time to get the ball under control.
However, he had the strength to hold off Antolin Alcaraz and drilled his shot past Al Habsi.
The departure of Evans at half-time led to Evra becoming possibly becoming United's shortest ever central defender.
He was limping too not long afterwards, although that proved to be a false alarm. There did not seem much wrong with the Frenchman when he went straight through the back of Moses anyway.
Jones curled the free-kick narrowly wide, which turned out to be Wigan's last opportunity before United struck again.
Valencia was having a quietly effective game and his prodded pass left Berbatov with enough space and time to smash his shot beyond Al Habsi.
Having fallen so far behind Manchester City in the goal difference stakes, United sensed it was time to start making up some ground.
Valencia's excellent performance continued when he drilled his first Premier League goal of the season into the bottom left corner.
Then, after Park was chopped down in the box by Alcaraz, substitute Rooney let Berbatov finish off his hat-trick.