West Ham manager Manuel Pellegrini endured a miserable afternoon as former club Manchester City scored three times in the first 34 minutes of a 4-0 win at the London Stadium.
The Chilean led City to the Premier League title in 2014 before being replaced two years ago by Pep Guardiola, who has taken the side to the next level, at least on the domestic front.
City needed just 11 minutes to open the scoring as Raheem Sterling's cross from the right deflected into the path of David Silva, who was able to steer beyond West Ham goalkeeper Lukasz Fabianski.
Sterling went from provider to goalscorer in the 19th minute, applying the simplest of touches into an empty net after Leroy Sane had driven a low cross into the six-yard area.
The pair then combined to devastating effect a quarter of an hour later, Sterling cushioning a pass to Sane, who turned past Hammers defender Fabian Balbuena before slotting past Fabianski.
By that stage, Pellegrini must have feared the worst as some home fans headed for the exit but it was not until the final seconds of the match that Sane scored again, tucking home from substitute Gabriel Jesus' cross.
The defending champions remain two points ahead of title rivals Liverpool, who brushed aside Watford 3-0 at Vicarage Road.
The deadlock was not broken until the 67th minute, when Mohamed Salah took his tally to 24 goals in his last 30 top-flight games with a fortuitous strike beyond Hornets goalkeeper Ben Foster.
Trent Alexander-Arnold's stunning 25-yard free-kick gave Foster no chance nine minutes later but Watford were given a lifeline when Jordan Henderson was given his marching orders after a cynical foul on Etienne Capoue resulted in a second yellow card.
The Reds finished strongly, though, with Roberto Firmino completing a comprehensive win by nodding in on the rebound after Sadio Mane had been denied by Foster.
Paul Pogba and Romelu Lukaku were restored to Manchester United's starting line-up but Jose Mourinho's men drew a blank against Crystal Palace at Old Trafford.
Both sides had their chances but the match finished goalless as United slipped 14 points behind rivals Manchester City.
Everton moved into the top six after Gylfi Sigurdsson's strike ushered the Toffees to a hard-fought 1-0 win over Cardiff at Goodison Park.
The Iceland playmaker tapped in just before the hour mark after Neil Etheridge had saved from Theo Walcott.
Claudio Ranieri started his reign as Fulham manager with a 3-2 victory over Southampton.
Aleksandar Mitrovic cancelled out Stuart Armstrong's 18th-minute opener just after the half hour before Andre Schurrle put the Cottagers ahead on the stroke of half-time.
Armstrong levelled for Saints on the resumption but Mitrovic's second in the 63rd minute proved decisive, leaving Southampton without a Premier League win since September 1.
Jamie Vardy's 79th-minute penalty rescued a 1-1 draw for 10-man Leicester at Brighton.
Glenn Murray headed Brighton in front on his 100th Premier League appearance before James Maddison collected two bookings in the space of two minutes just before the half hour.
But Vardy slotted home from the spot after Beram Kayal had upended Kelechi Iheanacho in the area.
