Tottenham increased the pressure on Manchester United manager Jose Mourinho with a convincing 3-0 win in the Premier League at Old Trafford Monday.
After a frenetic but goalless first half, Harry Kane's precise header put Spurs in command at the start of the second.
Lucas Moura's angled drive doubled their lead two minutes later as United's defensive frailties were exposed again.
The Brazilian rounded off the scoring late on, skipping past Chris Smalling to plant his shot beyond goalkeeper David de Gea.
Only a fourth league win at Old Trafford in 40 years maintained Tottenham's 100% record this season and lifted them to second in the table behind Liverpool.
United have lost two consecutive league games and two of their opening three fixtures for the first time since 1992-93.
A chastening, miserable night for Mourinho
United are only three games into the new season so it is very early for alarm bells to be ringing, but there is no escaping this has been a dismal start and this side Mourinho has assembled so expensively looks in no shape to challenge for the title.
The manner - as well as the margin - of this loss only increases the feeling of discontent around Old Trafford since the summer.
Mourinho will feel increasing heat but he can rightly point to the pivotal moment when, with United on top, Lukaku missed that simple chance after rounding keeper Hugo Lloris from Danny Rose's wayward pass.
There was no lack of effort from United's players but there was an element of collapse to their efforts after Spurs struck twice so quickly.
But this is currently a disjointed team, with Mourinho appearing to be scrambling to find a solution to the very obvious problems he faces in central defence.
He utilised midfielder Ander Herrera in a three-man central defensive system alongside the old guard of Phil Jones and Smalling - with Eric Bailly and Victor Lindelof paying the price for lamentable performances in the loss at Brighton.
It was obvious why Mourinho was desperate to add central defensive reinforcements, but he was also responsible for the acquisition of Bailly and Lindelof at a cost of more than £60m.
He will also be concerned at the complete lack of a response from his players once Spurs delivered that devastating one-two that effectively settled this game in their favour.
This was a chastening, miserable night for United and their manager.
Landmark night for Spurs?
Mourinho's troubles at United will rightly be the subject of so much attention, but this was a magnificent night for Spurs, who looked a force to be reckoned with.
Their players and supporters celebrated this superb victory in the manner that befitted what might just be a landmark night for Mauricio Pochettino's team.
It has been a charge regularly levelled at Spurs that they struggle to win games away at their closest title rivals. They put that right in the most emphatic manner possible.
Before this victory, Spurs had won only one of 12 league games against the so-called 'big six' since beating Manchester City in February 2016.
Pochettino had lost all four of his previous games at Old Trafford without scoring a goal, so this result will surely do wonders for Spurs' self-belief as they attempt to take the next step in their search for silverware.
Once they got into their stride, they simply accelerated away from United.
Kane's magnificent header established the platform, while the pace of Moura - fed brilliantly by Christian Eriksen for his first goal - simply carried too much pace for a leaden-footed United defence.
Spurs, after a slow start, grew in authority and how did Mourinho and United feel when they saw Toby Alderweireld's powerful defensive display with contributions of importance throughout? He was linked with United this summer but did not arrive.
In fact, when Alderweireld made a superb sliding challenge in the second half, some United fans turned towards executive vice-chairman Ed Woodward in the directors' box to make their feelings known.
For all the talk of Mourinho and missed transfer targets, it is worth remembering Pochettino did not buy any players this summer and can now reflect on three wins from three games this season.