Manchester United striker Robin van Persie scored a 94th minute equaliser to deny Jose Mourinho victory over his old boss Louis van Gaal at Old Trafford.
Mourinho looked set for victory in the battle against Van Gaal -- but deep into injury time Branislav Ivanovic was sent off for fouling Angel di Maria and Van Persie swept home a rebound from the resulting free-kick to make it 1-1.
Mourinho, who was clearly unhappy with Phil Dowd for giving Ivanovic a second yellow card for the foul, left Old Trafford with his unbeaten record intact.
But that will be of little consolation to the Chelsea boss, who will feel his team should have won.
Many had questioned whether, at 36 years old, Didier Drogba could fill the huge gap left by the absent Diego Costa -- but he headed home a Cesc Fabregas corner to give the Premier League leaders the lead in the 53rd minute.
It was vintage Drogba as he peeled away from his marker to glance the ball past David de Gea, but his job was made so much easier by the fact that 5ft 7in defender Rafael was the man marking him.
United did not look like getting back into a match in which Van Persie and Juan Mata, among others, had wasted good chances.
Chelsea looked perfectly organised at the back, but Van Persie was on hand to snatch a point.
When Mourinho, Van Gaal's former assistant at Barcelona, brought Chelsea to Old Trafford last season, they played out a painfully dull 0-0 draw in the early days of David Moyes' reign.
There was no hint of a repeat this time as both teams went for each other from the off.
Chelsea, well aware of United's defensive frailties, won two corners in the opening five minutes.
Oscar gained space in the box after an error by Marcos Rojo, but his deflected shot flew wide as United scrambled back to prevent an early goal.
Eden Hazard slipped past the ponderous Rafael, and the Brazilian was shown a yellow card for tugging his shirt.
The hosts hit back and broke through Di Maria, who worked the ball to the back post where Marouane Fellaini lurked, but the midfielder, making his first start of the season, could not finish. Mata then found Di Maria free in the box, but he volleyed over.
The pace of the match decreased somewhat as Chelsea were happy to allow United plenty of time on the ball and wait for opportunities to break.
That idea backfired, though, as United created chances. Januzaj, playing ahead of the injured Radamel Falcao, sliced open the Chelsea back four with a peach of a pass, but Thibaut Courtois rushed off his line to deny Van Persie, who wasted another chance moments later when he headed straight at the Chelsea goalkeeper.
The Blues, a far more physically imposing side than United, used their muscle to break up the hosts' attacks. Nemanja Matic body-checked Di Maria and Drogba went into the book for tripping Juan Mata.
Chelsea only found a sight of goal when United made mistakes. Rojo and Blind lost possession near the halfway line, but neither Willian nor Drogba could capitalise.
Rojo lost possession again but, luckily for the Argentine, De Gea was on hand to deny Drogba with his feet.
Mourinho, meanwhile, remonstrated with fourth official Chris Foy after Chelsea were not given a penalty when Ivanovic tumbled to the ground after grappling with Chris Smalling in the box.
Januzaj went close with a fierce drive, but Mata's shot was not so hot as he fired well over the bar from 15 yards just before half-time.
All that good work was undone within eight minutes of the restart. De Gea saved brilliantly from Hazard, but the Spaniard was picking the ball out of the net moments later when Drogba glanced home.
Ivanovic brushed off the challenge of Fellaini and Rojo but fired inches wide from a tight angle as Chelsea looked to kill the match off.
There seemed no way back for United, but Dowd showed Ivanovic a second yellow for a foul on Di Maria in the corner in the final minute of added time.
The Argentine found Fellaini with his cross but Courtois saved. The ball dropped at the feet of Van Persie, who drove home from close range to send Old Trafford into ecstasy.