London - Manchester United emerged undefeated at Stamford Bridge for the first time in Jose Mourinho's four visits to his old club, but Chelsea were the more grateful of the two sides for a point in a thrilling 2-2 draw on Saturday.
Substitute Ross Barkley struck with virtually the last kick of the game in the 96th minute to salvage the hosts' unbeaten start under Maurizio Sarri and spark a touchline melee as Mourinho took offence at the excessive celebrations of one of Sarri's backroom staff.
However, there were also positives for Mourinho as the visitors showed plenty of heart and no little skill to fight back from a goal down thanks to Anthony Martial's double.
AFP Sports looks at three things we learned:
Mourinho's struggles at Old Trafford are encapsulated in his troubled relationship with Martial, with the Frenchman failing to deliver on his rich potential over the past three seasons.
However, the 22-year-old cannot be accused of failing to play for his manager in his time of need.
Martial's composed equaliser transformed a game in which United had been outplayed for the first 55 minutes.
His second was an even sweeter finish that showed what United are capable of with Juan Mata and Marcus Rashford also playing their part in a flowing move.
"Martial is improving, he is doing different things than before," said Mourinho. "He is a more complete player than before but he needs to improve. He has a huge talent and he wants it, which is a good thing."
Sarri complained that Chelsea stopped playing "his football" after Martial levelled, and were too easily panicked into playing long balls.
Alvaro Morata again failed to act as a reliable focal point and his replacement Olivier Giroud is still without a goal this season.
The lack of an in-form striker has so far been papered over by the stunning form of Eden Hazard.
But the Belgian was blunted by some rough treatment by United early on as both Nemanja Matic and Ashley Young were booked.
On this evidence, Hazard can expect more bruises in the coming weeks as it becomes clear that if you stop him, the rest of the Chelsea attack is pretty blunt.
Unlike against Brighton, Tottenham and West Ham this season, United did not lose, but in common with those games they did once again concede from a corner.
Paul Pogba was at fault as Antonio Rudiger was given a free run to power a header past David de Gea and give Chelsea the perfect start.
Mourinho refused to criticise Pogba individually but for a coach whose success has been built on defensive solidity, patience with such a basic weakness is wearing thin.
"My feelings is that we work. We work on the pitch, the analysis, the preparation," said Mourinho.
"We defend mixed, so some of the players are in zone, some have individual opponents. Every player knows the zone or the man, but sometimes the opponent is better than us."