The Red Devils kept their perfect start under interim boss Ole Gunnar Solskjaer in tact thanks to Marcus Rashford’s first half goal.
Harry Kane looked to have given the hosts the lead in the first half, only for his goal to be chalked off by the offside flag.
But it was united who broke the deadlock just before half time, as Paul Pogba’s through ball found Rashford, who raced clear and fired home past Hugo Lloris.
Both sides had plenty of chances in the second half, as De Gea and Lloris were kept on their toes.
De Gea denied Kane and Alli several times as Tottenham searched desperately for an equalizer.
But United held firm to secure all three points, as Spurs’ title bid suffers another set back.
Here are the talking points…
Battle of the bosses
Much of the pre-match hype billed this encounter as Mauricio Pochettino’s interview for the United managers job.
The Spurs boss has been heavily linked with the role currently in the temporary hands of Ole Gunnar Solskjaer.
However it was Solskjaer who came out on top in this clash, as he maintained his 100% record since taking over from Jose Mourinho.
The Norwegian was full of praise for Pochettino during the week, but the advantage now lies with Solskjaer, who has made no secret for his desire to fill the role on a full-time basis.
Whilst Pochettino has done a superb job in North London, if United keep winning, the calls for Solskjaer will be harder to ignore.
He’s turned his game up another notch since Ole Gunnar Solskjaer’s arrival at Old Trafford – and Marcus Rashford is now showing he is the real deal.
Some pre-match statistics showed just why the 21-year-old is so special.
In a comparison with Harry Kane when he was the same age, Rashford had scored 14 more club goals, and 20 more in the Premier League prior to kick off.
He soon added another, firing past Hugo Lloris to give United the lead, and take his recent tally to four goals in six games under Solskjaer.
With 31 more international caps under his belt than Kane had at 21, Rashford is showing just how remarkable a talent he is, and could yet become.
99 not out
Speaking of stats, one that was doing the rounds on social media prior to kick off was that referee Mike Dean was sitting on 99 career red cards that he’s dished out.
For a man who is seemingly not shy when it comes to publicity, we’re sure Mr Dean will have been well aware he could reach a ton of dismissals in such a high-profile match.
The Wirral-born official headed into the match having shown six red cards in his previous six games – setting him up nicely to reach the milestone at Wembley.
Sadly for Dean he didn’t have chance to brandish his tenth red card of the season, and the 100 club continues to elude him.
But given that Dean has now shown nine red cards in 18 matches this season, it won’t elude him for long.
He has been widely regarded as one of the best in the business for some time now – and on this evidence, you’d be a fool to argue otherwise.
David De Gea pulled off a string of saves to keep Manchester United in front, and earn all three points.
First he thwarted Harry Kane with his feet, before diving full stretch to keep out Dele Alli’s header and United’s lead in tact.
De Gea was then equal to Christian Eriksen’s effort, before blocking Alli’s chance on goal, making a great reaction save from Toby Alderweireld, and then catching Kane’s free kick.
The onslaught continued, and Alli, Kane and Llorente were all again denied as De Gea proved impossible to beat.
It was an exhibition of goalkeeping of the highest order – and it was exceptional. Bravo.
Pogba is back
He’s faced his fair share of criticism this season, but Paul Pogba is performing to the levels we know he is capable of again.
Pogba had been almost frozen out in the old Mourinho regime after their well-documented fall out.
But Ole Gunar Solskjaer has got Pogba smiling again, and it’s paying dividends.
The Frenchman set up Rashford’s goal with a perfectly weighted pass, and was a thorn in Tottenham’s side all afternoon.
It was only for the goalkeeping abilities of Hugo Lloris that the 25-year-old didn’t get his name on the scoresheet.
His unplayable at his best, and his form can only mean good things for United.
Spurs need midfield reinforcements
There were slightly concerning scenes for Spurs fans as Moussa Sissoko pulled up abruptly when chasing a ball downfield.
The Frenchman was eventually subbed for Erik Lamela after aggravating what looked to be a hamstring injury – leaving 18-year-old Oliver Skipp as the only other recognised midfielder on the bench.
With Moussa Dembele reportedly on the verge of a transfer to China, and with Son Heung-Min heading off for the Asian Cup, a length lay off for Sissoko would leave Tottenham desperately light of midfielders.
Mauricio Pochettino is already without Eric Dier, Victor Wanyama and Lucas Moura, and surely signing a midfielder is top priority before the transfer window closes.