Cesc Fabregas and Eden Hazard were brilliant all game long and opened the affair with a goal. Hazard found Fabregas for the score to put Chelsea in front in the fifth minute.
But Big Sam's side rallied and struck twice in the following 10 minutes to take the lead. Wilfried Zaha scored another excellent solo goal from the top of the box, and Christian Benteke showed great composure to flick the ball over the onrushing Thibaut Courtois following a blistering counter attack.
A heroic goalkeeping performance by Wayne Hennessey assured Sam Allardyce's side would continue their fine run of form with a highly improbable win at the home of the best team in England.