Chelsea lost more ground on the top four as West Ham battled back to earn a point at the London Stadium.
A fast start from the Blues saw Joao Felix have a goal disallowed on his second Blues start, before the Portuguese fired the visitors in front from Enzo Fernandez's fine cross.
Kai Havertz then put the ball in the net again only for it to be disallowed, before ex-Blues left-back Emerson popped up at the back post to level after a Jarrod Bowen flick-on.
West Ham's Tomas Soucek saw his close-range effort chalked off by VAR in the second half, before the Czech escaped a late handball scare as Chelsea appealed for a penalty.
Here are the game's talking points.
1. Joao Felix could be the one that knits it all together
You could be forgiven for having forgotten about Joao Felix. He arrived at Chelsea all the way back on January 11 after all, and the Blues have signed five players since then.
But now free from the purgatory inflicted on him following that, let's face it, pretty funny red card less than an hour into his debut at Fulham, the Portuguese was unleashed for his second appearance for Potter's side, and he impressed right from the start.
In a squad now full of nippy players who are happiest out wide - Noni Madueke and Mykhaylo Mudryk started here, but there is also Raheem Sterling, Hakim Ziyech, Christian Pulisic and probably some more... oh, Callum Hudson-Odoi - Felix is built different.
He looks perfect for the No.10 position behind the roving menace that is Kai Havertz, something that is likely to be bad news for Mason Mount should, as expected, his loan deal become a permanent move.
Felix was superb from the start here, giving an attacking structure and dynamism to a Chelsea side which could have ran over West Ham in the early stages, with his smart finish just reward for his work.
2. Enzo Fernandez shows his creative side
That finish came from a superb Fernandez pass, with the Argentinean also making his second appearance for Chelsea after his debut last week.
In such moments it is easy to write something as flippant as this was the new boy "proving his worth", but then you have to remember that he cost £107m.
Can you ever prove to be worth that much? No, but this was a nice snapshot of what he can do.
3. Even more new players may be needed
With the attacking positions pretty much sorted, for now at least, could Chelsea embark upon a similar spree in the summer as they remodel the defence?
For all the changes at the club their best centre-back remains a 38-year-old, and although Thiago Silva thoroughly deserves the new contract he got in the week, he isn't going to be around forever.
Alongside him here was Benoit Badiashile, signed all the way back on January 5, and already deemed not good enough for the Champions League squad.
Marc Cucurella isn't good enough full stop if you believe a growing number of Chelsea fans, and it was from his side that Vladimir Coufal was able to send in the cross which Bowen flicked on for Emerson to score.
Cucurella had initially lost the ball and was played around before the cross, and he was to depart midway through the second half.
4. Scrapping Irons
You can pretty confidently say that West Ham would have faded quickly in this game earlier in the season, with Chelsea's onslaught in the first half probably enough to blow them away.
To the credit of David Moyes' side though, they hung in there, with the first half introduction of Soucek for the injured Lucas Paqueta helping with that.
Soucek is a player who has played a lot of football over the past couple of seasons, and that has told in his performances this campaign.
The likes of Paqueta, who was starting for Brazil at the World Cup, were obviously signed to provide a different dimension to West Ham, but every so often clubs need to remember who they are.
Soucek is a solid citizen who has served West Ham well, and he found the energy levels to drag his side back into the game, almost winning it with his effort which was disallowed.
5. When will Chelsea start winning?
That's now just one win in the last seven league games for Chelsea, who remain in Premier League purgatory in the middle of the table.
It's still all so new of course, and you get the feeling they'll gel eventually. There were signs here that that might not be too far away.
But will it be soon enough to save this season? And indeed Graham Potter in the immediate future?
It's all still something of a mess.
