Overnight food poisoning at the team's Docklands hotel had almost caused the 11th-hour postponement of this thrilling encounter, which was only played at the insistence of the FA Premier League despite Martin Jol's pleas for a 24-hour delay to the kick-off.
But in the end, a Thierry Henry hat-trick for Arsenal in their victory over Wigan Athletic at Highbury, allied to Yossi Benayoun's late West Ham winner, combined to send Arsene Wenger's side leapfrogging over their fiercest rivals into that precious fourth spot.
After assessing the damage caused by last night's hotel buffet, Jol only made two changes from the side that beat Bolton Wanderers at White Hart Lane last week, as Stephen Kelly and Edgar Davids came in for Paul Stalteri and Danny Murphy, but his side were clearly below par.
Alan Pardew, who has a mini injury crisis of his own ahead of next week's FA Cup final, could at least take some comfort from the return of Paul Konchesky, Anton Ferdinand and Benayoun, while Teddy Sheringham also started against his old club as West Ham made four changes from the side that beat West Bromwich Albion on May Day.
Any notion that the East Enders would be taking it easy with the Millennium in mind were quickly dispelled, though, and after Sheringham and Nigel Reo-Coker went agonisingly close in the opening exchanges, Carl Fletcher put the Hammers ahead with just 10 minutes on the clock when he cracked a low 20-yarder between the diving Paul Robinson and his left-hand post, to claim his first-ever Premiership goal.
Although Teemu Tainio headed ex-Hammer Michael Carrick's well-flighted corner just inches over, teetering Tottenham looked anything like a side which needed victory to edge itself onto the doorstep of the Champions League.
Indeed, West Ham's superior energy and drive was all too apparent as Benayoun, Sheringham and goalscorer Fletcher each threatened Robinson during a series of East End raids.
But as the Hammers know only too well from first-hand experience, you ignore Jermain Defoe - who scored 41 goals in 105 claret and blue outings - at your peril.
And, sure enough, the heavily-jeered striker silenced the home supporters 10 minutes before the break when he turned cleverly and threaded a low, angled 15-yard equaliser beyond the outstretched palm of Shaka Hislop and inside the groping 'keeper's right-hand post, to bag his ninth goal of the campaign.
On returning to the sanctuary of the Upton Park dressing rooms, Jol's men discovered that rivals Arsenal were all-square with Wigan at the interval, too.
However, just seven minutes into the second half, two Spurs old boys looked to have put the north Londoners back into trouble when Bobby Zamora was upended by Tainio in the box, but Sheringham's poor penalty was easily saved by Robinson.
The veteran's nightmare miss ironically kept his former team's Champions League dream alive, but within minutes news filtered through from Highbury that Thierry Henry had fired the Gunners ahead on their way to a 4-2 win.
And although Defoe forced a fine parry from Hislop, that was the closest Spurs would come to turning the heat back onto their north London neighbours.
For with just 10 minutes remaining, Shaun Newton invited Benayoun to embark on a mazy dribble that climaxed with him firing West Ham to victory and ninth place from eight yards.