Brentford substitute Fabio Carvalho tapped in an 93th-minute equaliser to deny Chelsea victory in a dramatic London derby.
Carvalho, 23, had been on the pitch for less than four minutes before turning in from a long Kevin Schade throw-in.
It had looked as if Chelsea substitutes Cole Palmer and Alejandro Garnacho would steal the headlines.
With the visitors a goal down, Palmer swept in a first-time volley to equalise just after the hour mark, having only been on for five minutes.
Then Garnacho, recently signed from Manchester United, helped set up midfielder Moises Caicedo to power in a shot past Brentford goalkeeper Caoimhin Kelleher in the 85th minute.
Brentford had deserved their half-time lead – forward Schade struck in the 35th minute shot after Jordan Henderson’s long ball had sparked a counter-attack.
Chelsea head coach Enzo Maresca dipped into his vast playing resources by making three half-time changes in response.
Reece James, Marc Cucurella and Tyrique George came on for debutant Facundo Buonanotte, a deadline-day loan signing from Brighton, Jorrel Hato, another new arrival, and Wesley Fofana, making his first start since recovering from a major hamstring injury.
Maresca had picked a starting line-up with the aim of resting key players for their return to the Champions League after a two-year absence this week. But it didn’t work, and he had to call on them – with Palmer also coming on early in the second half to replace winger Jamie Gittens.
Chelsea remain fifth after four Premier League matches – and now turn their attentions to Bayern Munich in the Champions League, before returning to domestic action against Manchester United. Brentford, meanwhile, sit 12th.
Analysis: Brentford throw-ins cause ‘chaos’
Keith Andrews was promoted to the Brentford head coach’s role after serving as their set-piece coach. His impact on the team is clear.
Chelsea were peppered with long throw-ins from defender Michael Kayode throughout the match. When he went off in the second half, someone else had to step up.
Schade, having scored with his feet, launched the ball into the box to set up a goal with his hands and when asked about his impact, Andrews said: “That’s quite unique, isn’t it? Yes, it is.
“But it’s not unique for this football club, I must say. I find with the modern game, and it’s always been the way when the top teams do it, it’s accepted. It’s OK to do. It’s been a prevalent part of what this club has done for numerous years.
“I was obviously in a different role last year, where we caused a lot of chaos from situations like that. We’ll always try and find ways to get results and win games. It’s nice that we’re able to have multiple players able to take long throws.
“If you feel a long throw will help you with what you’ve got, A, the delivery and B, the physicality, to be able to cause problems and create opportunities, then I think it would be foolish not to use it.”
Maresca added: “The problem is that they have Kayode, they have [Mathias] Jensen, they have [Ethan] Pinnock, and then Schade at the end. I think we tried to deal with that, knowing that they are so dangerous, because they can arrive in the six-yard box very easily.”
Andrews also said substitute Carvalho will become a “big player for this football club” and he praised Henderson, as England manager Thomas Tuchel watched on.
