A classic Manchester United away performance was required, and that's exactly what Sir Alex Ferguson's side produced on this day in 2009.
Heading into the match without a number of key defenders, the odds looked to be stacked against the visitors, but the defending champions were clinical on their way to a 4-0 triumph at Upton Park.
Darren Fletcher would start the game at right-back, while knocks picked up by Gary Neville and Wes Brown over the course of the 90 minutes would force both Michael Carrick and Ryan Giggs to move into defence.
Despite the one-sided scoreline, it was a nervy start from United as a poor pass from Giggs allowed Zavon Hines to cross for Jack Collison, who was only denied a goal when his fellow Welshman recovered to make a vital tackle at the back post.
Ferguson's side improved as the first half progressed, and it was another of United's experienced men who broke the deadlock in stoppage time when Paul Scholes latched on to Darron Gibson's header before firing past a helpless Robert Green.
Gianfranco Zola was left disappointed as his West Ham side went in at the break behind, and the misery was piled on the Italian just after the hour mark when United doubled their advantage.
Wayne Rooney had been kept quiet for much of the match, but the England striker found the space he craved to exchange passes with Giggs to set up Gibson, who unleashed an unstoppable strike from the edge of the box to leave Green watching the ball hit the back of the net once again.
On a rare appearance in goal, Tomasz Kuszczak protected United's advantage by getting a strong hand to a curling free kick from Alessandro Diamanti.
Rooney played a key role in creating his side's third in the 71st minute with a clever exchange on the left wing with Anderson, which allowed Antonio Valencia to tap in from close range.
A minute later, Rooney added a goal to complete his fine display by finding the space inside the box to convert Valencia's inviting cross.
After the game, Ferguson was left in no doubt as to which moment was the turning point in East London.
"It's always a hard place to come to. Scholes's strike was a great goal to get at an important time. He's capable of scoring outside the box. It was a wonderful hit," the United boss told reporters.
United would keep the pressure on leaders Chelsea with the win, but their title defence would eventually end in disappointment as Carlo Ancelotti took the famous trophy back to Stamford Bridge.
West Ham: Green (Kurucz), Gabbidon, Tomkins, Spector, Ilunga, Parker, Kovac (Dyer), Collison, Stanislas, Hines (Diamanti), Cole
Man Utd: Kuszczak, Fletcher, Neville, Brown, Evra, Anderson, Giggs, Scholes, Gibson (Berbatov), Valencia, Rooney (Owen)