Manchester City displayed familiar champions' swagger and Mo Salah rediscovered his goalscoring touch for Liverpool as the two title favourites forged clear at the top of the English Premier football League.
City destroyed Burnley 5-0 before Salah broke his mini scoring drought in Liverpool's laboured 1-0 win at Huddersfield Town, yet it all paled beside the drama that once again engulfed Manchester United and Jose Mourinho in the day's marquee match.
Mourinho's side had been poised to earn a comeback win at unbeaten Chelsea until a stoppage-time equaliser from substitute Ross Barkley earned the Blues a 2-2 draw and sparked a pitchside pantomime.
The Portuguese was enraged by the provocative, in-your-face celebrations of Marco Ianni, one of Chelsea manager Maurizio Sarri's assistants, after the 96th-minute goal and had to be restrained as he tried to pursue his tormentor down the tunnel.
The charmless episode left Sarri accepting that the Chelsea bench was in the wrong and ordering his assistant to apologise to Mourinho.
Mourinho accepted the apology but the insult for him was certainly not as bad as missing out on all three points that his under-pressure side would have deserved.
He called it an "awful" result after one of their better performances of a chequered season and when City later destroyed Burnley with four second-half goals, it meant United, now ninth, are nine points behind their neighbours.
City's latest masterclass, with goals from Sergio Aguero, Bernardo Silva, Fernandinho, Leroy Sane and Riyad Mahrez, brought manager Pep Guardiola as much delight as seeing Kevin De Bruyne back in action off the bench after his injury layoff.
City moved onto 23 points, ahead only on goal difference from similarly unbeaten Liverpool who, far from their best, were grateful for Salah's sharp first-half winner in their unconvincing slog at Huddersfield.
It was the Egyptian's 50th goal in English football but only the fourth this term for last season's Golden Boot winner.
Manchester City and Liverpool are two points clear of Chelsea, who escaped with their unbeaten record intact, and Tottenham Hotspur, who earned a hard-fought 1-0 win at West Ham United courtesy of Erik Lamela's deft header just before halftime.
At Stamford Bridge, Mourinho's side had gone one down when Antonio Rudiger escaped his marker Paul Pogba to head home unopposed from a corner.
They rebounded with two second-half Anthony Martial goals and looked largely in control until Barkley saved the day.
The dramatic finish was then overshadowed by the late scuffle, which had been instigated by Ianni's celebrations that Mourinho noted were "very impolite."
They evidently also irritated Sarri who was at pains to apologise to Mourinho himself.
"Of course, I want to speak to him again because I want to make sure he's able to understand it was a big mistake," he said.
Bournemouth missed the chance to slip into the top five as they were held to a goalless draw by south coast rivals Southampton while Watford checked Wolverhampton Wanderers' impressive progress at Molineux with a 2-0 win.
Wolves fielded the same side for a record ninth straight Premier League game but were undone by two superb goals in the space of 58 seconds midway through the first half from Etienne Capoue and Roberto Pereyra.
Cardiff City leapt out of the relegation zone in some style, beating Fulham 4-2 -- the first time they had bagged four goals in a top-flight match since 1961 -- but Newcastle United's woes under Rafa Benitez continued.
The Magpies slumped to the bottom of the league on just two points after losing 1-0 at home to Brighton & Hove Albion, whose day was only marred by an injury to their top striker Glenn Murray.
Murray landed heavily after an aerial challenge and was taken off on a stretcher after six minutes of treatment on the pitch but he was later reported to be fine after precautionary scans at hospital.