Ross Barkley scored an injury-time equaliser as Chelsea salvaged a 2-2 draw with Manchester United on a dramatic afternoon at Stamford Bridge.
Anthony Martial had struck twice as United came from a goal down to lead 2-1, but Jose Mourinho was denied a happy return to his old club when substitute Barkley scrambled home in the fifth of six added minutes.
The United manager then had to be restrained by a steward after reacting angrily to something that appeared to have been said during the Chelsea bench's celebrations.
Antonio Rudiger, who lost Paul Pogba at a corner, had put Chelsea in front, but Martial lashed home to level before the break and produced a superb second that looked to have won the game only for Barkley to strike after David Luiz's header hit the post and Rudiger's follow-up was saved.
United made a purposeful start in the London sunshine, Ashley Young almost finding Marcus Rashford in space only for Luiz to make a key interception.
But back came Chelsea, and Eden Hazard was unable to get a clean connection inside the area after Willian had pulled the ball back to him.
N'Golo Kante had a long-range strike blocked before, with 10 minutes gone, the home side won a dangerous free kick when Nemanja Matic fouled Hazard only for Willian to balloon his effort well over the top.
Matic fouled Hazard again moments later, this time inside the United half, and became the first player to be booked.
United's Romelu Lukaku looped a header wide after Luke Shaw picked up the pieces and crossed when a free kick had been cleared, and then Juan Mata found Martial free to win a corner that came to nothing.
With 21 minutes gone, Hazard drilled the ball across the six-yard box, United scrambling it away for a corner -- and from it, Chelsea went ahead as Rudiger was left free to bullet a header past David De Gea and into the corner, Pogba having failed to pick up his run.
The goal put United on the back foot, Hazard almost getting clear moments later and then being brought down by Young, who was booked, as Mourinho's side began to look a little ragged.
As the half-hour approached, there were faint United appeals for a penalty after Rashford went to ground when Luiz barged into him, but referee Mike Dean waved them away.
Hazard went into the book for fouling Rashford after the ball had broken to the United forward down the right, but Mata's free kick was cleared.
Alvaro Morata fired over from outside the area with Chelsea in control, but United sparked into life towards the end of the half when neat build-up ended with a Pogba pull-back being cleared.
Maurizio Sarri's side were close to doubling their lead in the opening moments of the second half, Morata finding space but producing a scuffed strike that was held by the diving De Gea.
Luiz latched on to a wonderful Hazard backheel to earn Chelsea a corner, but United responded by launching the spell of pressure from which they levelled after 55 minutes, Mata's deflected shot saved by Kepa and the follow-up cross half cleared before Martial controlled and lashed home.
Hazard tried to get the Londoners back on the front foot, two dangerous darts winning them corners that United defended easily, and with 66 minutes gone they were within inches of retaking the lead as Luiz's flicked header from a free kick bounced just wide.
Mata was booked for a scything challenge on Cesar Azpilicueta on the edge of the Chelsea area, and two minutes later Sarri made the first change of the afternoon as Barkley replaced Mateo Kovacic.
The Blues were almost back in front after 71 minutes, De Gea making a fine one-handed save from Kante's fierce effort, but within a minute they were behind as Martial struck again, turning to lash low beyond Kepa from just inside the area after Mata and Rashford had made the opening.
Pedro replaced Willian as a frustrated Sarri tried to reinvigorate his team for the final quarter of an hour, Mourinho responding with a change of his own as ex-Chelsea star Mata came off to be replaced by Ander Herrera.
With the final 10 minutes approaching, Chelsea brought Olivier Giroud into the fray to replace Mata, and Mourinho took off goal hero Martial for Andreas Pereira and replaced Rashford with Alexis Sanchez.
Azpilicueta lashed well over from outside the box as the 90 minutes came to an end and Sanchez and Pereira were booked for fouls as the clock ran down before Barkley had the last word from close range.