Chelsea played out a 3-3 draw with West Brom at the Hawthorns on Saturday evening.
Frank Lampard's side came back from three down to seal a point at West Brom.
Chelsea manager Frank Lampard says he cannot 'legislate for their mistakes' in their 3-3 draw with West Bromwich on Saturday evening.
The Blues were three goals down at half-time but they responded in the second half after Lampard made a few changes to his side at the Hawthorns Stadium.
Striker Tammy Abraham's last-gasp goal ensured the west London club and West Brom shared the spoils on the day.
The Baggies ran riot over the Blues in the first half as a double from Callum Robinson and a cool finish from Kyle Bartley made it 3-0 at half-time.
Chelsea responded 10 minutes into the second half through Mason Mount and substitute Callum Hudson-Odoi topped it up by putting the ball in the bottom corner following a great 1-2 move.
And, Abraham, who missed a brilliant chance in the first half, wrapped up the comeback in extra time with a close-range finish after goalkeeper Sam Johnstone parried midfielder Kai Havertz's shot.
Following the draw, Lampard told Sky Sports: "It is two points lost at the end of the day - and that's no disrespect to West Brom. You come here and you know the transition and any mistakes would be something they would jump on - that and set pieces. You can't legislate for the mistakes that there were today.
"It was mistakes, clear mistakes [that cost us]. You can have as many meetings as you want but with those mistakes you give yourself a mountain to climb. [We lacked] a bit if urgency in the team.
"We created two or three great chances in the first half. I felt we would create more, the only other problem at 3-0 was West Brom were going to protect their lead more. It is a big lesson for us. We will get a lot better, we're still finding our way with new players and a lack of pre-season. Today is part of the process of getting better.
"There is a lot we can keep getting better at. I'm not going to criticise every part of our game, I think they had three shots on target and got three goals. There were genuine mistakes. There was nothing tactically you can analyse again and again - there were just pure mistakes."
Winger Hudson-Odoi said while speaking to BBC Match of the Day: "At 3-0 we wanted to try to get the points and had the feeling that we would get the goals.
"We felt it was on and put a lot of pressure on straight away in the second half.
"It was good, we worked hard, got the ball wide early, kept playing and got the goals.
"The new boys have gelled really well. All worked hard. They've improved us and have shown they are quality players with the right mentality to win games."