Tottenham suffered their biggest home defeat of Andre Villas-Boas' reign as West Ham ran riot with a stunning second-half display at White Hart Lane.
The Hammers scored three stunning goals in 13 minutes to come away with their first victory at White Hart Lane since 1999.
Winston Reid started the rout with a goal from a corner, Ricardo Vaz Te doubled the lead and then Ravel Morrison scored a superb solo strike to seal the 3-0 win.
Sam Allardyce had described his West Ham team as "relegation favourites" earlier this week, but on this evidence, the east London side will have no trouble staying up.
Much had been made of West Ham's lack of goals this term because of the absence of Andy Carroll, but the way in which the Hammers took their goals will delight Allardyce, and the visiting fans, who revelled in gaining the bragging rights over one of their arch rivals.
As for Tottenham, the bubble of happiness that came with the arrival of seven new players has now burst. Boos rang out from the home fans at the final whistle. They know there is still much work to do if they are to mount a top-four challenge.
A midweek trip to Russia looked to have taken the sting out of Villas-Boas' side, who lacked a cutting edge throughout.
Despite being underdogs, West Ham had the better of the opening exchanges.
Mohamed Diame sneaked into the Tottenham box, but Jan Vertonghen and Paulinho did just enough to put the midfielder off.
Stewart Downing then whipped in a cross from wide, but Kevin Nolan could only head wide.