Frank Lampard warned his Chelsea side they must quickly cut out basic mistakes but insists the Blues remain a work in progress after fighting back for a 3-3 draw at West Brom.

Chelsea were staring down the barrel of an unexpected defeat at The Hawthorns after an inept display of defending saw them 3-0 down inside 27 minutes.

Errors from Marcos Alonso and Premier League debutant Thiago Silva saw Callum Robinson score twice before Kyle Bartley benefitted from more poor defending at a corner.

But Mason Mount and substitute Callum Hudson-Odoi brought Chelsea back into the game before a third academy graduate in the form of Tammy Abraham rescued a point in injury time.

"It's two points dropped and that's no disrespect to West Brom," Chelsea boss Lampard told Sky Sports. 

"But to come here and sort of understand the game and know that transition and mistakes is something they'd try to jump on, counter-attack against us and [use] set-pieces – we spoke about it before the game and you can't legislate for pure mistakes, which they were today. 

"Then it gives you a really difficult game to get back in to. I can laud character because we showed character and persistence but we didn't need to if we did things properly in the game.

"They were clear mistakes, the first one Marcos heads it into the middle of the pitch for them to make the transition. The Thiago one is a mistake, he's been around long enough to know that and we'll certainly give him that one in his first game. Then Marcos loses his man for the third goal from the corner. 

"You can do as many meetings as you want, if you make those mistakes you're going to give yourself a mountain to climb."

Lampard felt the introductions of Cesar Azpilicueta and Hudson-Odoi at half-time brought a different dimension to Chelsea.

"It brought a bit of urgency, a bit of speed of pass to move it," he added. 

"Azpi brings personality straight into the team even at left-back. Callum one-v-one brought something different, he got at people. Those are things Callum can and needs to do, he made a big difference."

Lampard said the fact Chelsea created going forward meant it was an easy message to try and lift his team at the break and is convinced a new-look squad will come good.

"We created two or three really great chances in first half and i thought we'd create more," he said. 

"The only problem when you're 3-0 down is West Brom are going to seriously protect the lead which means dropping back, frustrating moments and it was about staying patient. We did that to a big degree. 

"But it's a lesson for us in the detail of a game, it doesn't how much you create, and we will create a lot, we will get better.

"We're definitely finding our way with new players in the team and a lack of pre-season. 

"Part of the process of getting better is accepting things that aren't right in our game today because we lost two points."