West Bromwich Albion went third in the Premier League with a 4-2 win against Sunderland at the Stadium of Light.
Zoltan Gera curled in a brilliant 20-yarder just before the half-hour mark, then Simon Migonlet's inexplicable failure to hold a routine through ball allowed the alert Shane Long to finish into an empty net.
Craig Gardner pulled one back with a deflected free-kick before Romelu Lukaku restored the two-goal cushion from the penalty spot.
Stephane Sessegnon then smashed in a close-range effort, before Marc-Antoine Fortune had the final word for West Brom, scoring with the last meaningful kick of the game.
Steve Clarke's men leapfrog his former club Chelsea after notching up their eighth win of the season.
It is the first time West Brom have won four straight top flight games since October 1980, when they finished the season fourth.
Although such an outcome remains a very long shot, there is no fluke about their early-season success.
Clarke deserves plaudits for building a well-organised side that is comfortable on the ball and capable of devastating work on the counter-attack.
He has taken Roy Hodgson's solid foundations and added spark and sophistication - particularly the excellent Claudio Yacob in midfield.
Stephane Sessegnon looked Sunderland's liveliest player. He tested Boaz Myhill with a low shot in the fifth minute, and another on 17 minutes after good work from Danny Rose and Adam Johnson. He then forced Myhill into action with a glancing header from Sebastian Larsson's free-kick.
Despite Sessegnon's efforts, West Brom controlled the game, enjoying 70 per cent possession early on and troubling the home defence, particularly John O'Shea.
The Irishman was booked for a foul on Long early on, and then rode his luck with another foul on his countryman Long - ref Mike Dean got his cards out again, but only to show the West Brom player a harsh yellow card for diving.
Gera opened the scoring with a cracking left-foot strike from range, curling it deliciously past Mignolet.
Then the goalkeeper had a moment of madness, as he slid out to collect a Brunt pass, but let it squirm out of his grasp and Long pounced to net the easiest of finishes.
Sunderland looked devoid of ideas until Gardner finally brought some noise from a muted crowd with his free-kick that clipped the top of the wall and arced into the net via a weak hand from Myhill.
Lukaku appeared to put the game out of Sunderland's reach with an emphatic penalty - won by Liam Ridgewell with what looked like a dive.
But again Sunderland came back, as Sessegnon whacked in the rebound after Myhill parried a Steven Fletcher header.
As Sunderland poured forward, West Brom hit the on the break - Lukaku found Fortune, who found the bottom corner to add some sparkle to another impressive performance.
MAN OF THE MATCH
Claudio Yacob (West Brom): This was a consummate team performance, but Yacob just about shades it with his excellent passing, which set the tempo in midfield.
SUNDERLAND: Mignolet 5, Bardsley 6, Rose 6, Cuellar 6, O'Shea 5, Cattermole 6, Colback 5, Larsson 6, Johnson 5, Sessegnon 7, Fletcher 5. Subs: Gardner 7, McClean 7, Saha 6.
WEST BROM: Myhill 6, Ridgewell 7, Jones 6, McAuley 7, Olsson 7, Yacob 7, Gera 7, Brunt 7, Morrison 7, Odemwingie 7, Long 7. Subs: Lukaku 7, Tamas N/A, Fortune 7.