With this dramatic victory Tottenham Hotspur sent a missive to the other challengers for a Champions League berth next season.
A night that began with a tribute to the sadly departed Bobby Moore, who passed away 20 years ago, ended with Spurs continuing to suggest they are stronger now than under Harry Redknapp, who took them into the European Cup once and was denied a repeat only by Chelsea winning the competition last season.
The Blues' insipid display in losing at Manchester City 2-0 on Sunday had handed the initiative to Tottenham and the Andre Villas-Boas project was posting a statement to Chelsea, Arsenal, and even City. The message said that they were not going away and that Roberto Mancini's men could be reeled in from second, where they stand on 56 points, and Chelsea and Arsenal might be shoved into a dogfight for the final Champions League berth.
After this Monday night encounter under Upton Park's lights Spurs next five league games were Arsenal at home, Liverpool (away), Fulham (h), Swansea City (a) and Everton (h). Factor in the two legs of an Europa League last-16 tie against Internazionale also crammed into the sequence and the challenge was for Villas-Boas's gang to screw their courage to the sticking place and go on a season-defining run to propel them to Spurs' highest Premier League finish of second or third.
Prime movers in last term's fourth position were Luka Modric and Rafael van der Vaart. They have since departed, and Spurs's opener illustrated the new hierarchy under Villas-Boas (below), Redknapp's successor, who seeks to move them towards a permanent place in the elite class.
Slick midfield interplay involving the outstanding Gareth Bale, Scott Parker, Aaron Lennon, Lewis Holtby and Mousa Dembélé ended with the latter threading a pass in to Emmanuel Adebayor. Guy Demel became the patsy in the move by intercepting this and hitting the ball straight to Bale.
The player no opposition wants to collect just outside their area, waltzed toward goal to leave James Collins a spectator and fired beyond Jussi Jaaskelainen. This was Bale's 14th goal of the Premier League season and made him the player who has scored the last five for Spurs in the competition.
"Pretty unstoppable" was Sam Allardyce's pre-match verdict as the West Ham manager hoped the footballer beginning to be touted as a Welsh Cristiano Ronaldo might have "an off night".
According to Opta, Tottenham had won only 23 of 95 Premier League London derbies away from home. Twelve minutes after Bale's first goal West Ham suggested Spurs might not improve this statistic. Parker, who became this manor's first Football Writers' Player of the Year in 2011 since Moore in 1964 before he moved to Spurs, clipped Andy Carroll, and the forward stepped up to notch the penalty awarded by Howard Webb.
Received wisdom said Villas-Boas's mid-season sacking by Chelsea last year would be followed by another dismissal by Daniel Levy, the Spurs chairman. Instead the Portuguese has proved he learned from the clumsy man-management and willingness to pick fights with the press that contributed to his downfall.
He continues to surprise the cognoscenti. The revelation that Villas-Boas has no use for high-powered analysis seemed a contradiction from a manager whose discourse can stray into double-speak.
"I have never used Prozone. I don't use it because I don't believe [in it]," he said. "You always have to be very, very careful with statistics. It doesn't mean that we negate them completely. We have a scientific department that deals with that but we don't prepare our training or players based on the physical data we get from matches. The mind and how the player feels is much more important for us, rather than statistical data."
Villas-Boas did not need a computer to see how Steven Caulker (twice) and Adebayor should have given his side a lead before Joe Cole's sweet finish two minutes after the Togolese missed the rebound from a Gylfi Sigurdsson shot that hit the post.
The tributes to West Ham's finest player had included the squad wearing t-shirts that bore "Moore" and the No6 that was retired five years ago, and the tender touch of his three grandchildren leading the teams out.
David Gold, West Ham's co-chairman, told the BBC: "If Bobby Moore had been alive today we'd all have realised he was a great player, a man who won a World Cup, but also a gentleman and an honest man as well. He'd be a superstar today had he not been taken by cancer."
Moore, of course, would have wanted victory but he would have admired the determination that drove Spurs to equalise through Sigurdsson's 76th-minute effort and the sublime beauty of Bale's late, late winner.
Their rivals, too, will take note: this is a different Welshman in a different Spurs team, now.