West Ham manager Slaven Bilic
Slaven Bilic's side were poor for long periods and once again conceded late on at the Bridge to drop points, just as they did last season.
Antonio Conte got life in West London off to a winning start thanks to a penalty from Eden Hazard and a fine late strike from Diego Costa.
West Ham looked like they may go on to snatch an unlikely point when James Collins smashed home a superb half volley in the box to make it 1-1 in the second half.
Some lackadaisical play in possession on the halfway line gifted Chelsea a counter attack and Costa punished the Hammers with a fine finish into the bottom corner from outside the box.
Here's five things we learned about West Ham in the battle of East vs West London:
Andre Ayew didn't last long on his debut
1) Hammers injury curse is real
It was so typical of West Ham's luck - or lack of it - that cub record £20.5 million signing Andre Ayew was injured less than half an hour into his debut. It proves, if there was ever any doubt, for even the least superstitious Hammers fan that the club's injury curse is real as the striker faces a long spell on the sidelines.
All clubs have their fair share of injuries over the course of a season but West Ham seem to suffer more than most, particularly when it comes to strikers.
The list of players who have gone the same way is endless with Dean Ashton the most notable and other big names like Craig Bellamy, Andy Carroll spending more time in the treatment room. Who can forget Keiron Dyer and Freddie Ljungberg while even last season Bilic lost Dimitri Payet, Manuel Lanzini, Winston Reid, Diafra Sakho and Enner Valencia all at the same time, which ultimately cost the club a place in the Champions League.
2) Antonio fast becoming Slaven Bilic's Achilles heel
If you lined up every single West Ham fan on the planet and asked each one whether they thought Michail Antonio was a right back not one would say 'Yes'. Why then does the only person that matters, Slaven Bilic, not see it.
The former Croatia boss has persisted with the powerful winger-cum-forward at right back despite a brilliant contribution of 15 goals and assists between December and May last season.
Not only is Antonio not good enough to play at right back for West Ham, he is also completely wasted there.
It is the biggest bone of contention Hammers fans have with Bilic and it is fast becoming his Achilles heel at West Ham.
West Ham co-owners David Sullivan and David Gold
3) Hammers owners kidding themselves if they think squad is strong enough
There has been a lot of talk from West Ham co-owners David Sullivan and David Gold this week that they are all but done in the transfer window and happy with the business.
Most Hammers fans would disagree and promises of a major marquee signing have not materialised. Instead the club has been talking up Ayew, who has never scored more than 12 goals in a season, and now he is injured.
Yes it's still very early days but Bilic's signings Havard Nordtveit and Gokhan Tore looked like downgrades on the likes of Alex Song and Victor Moses on this evidence.
The club must bring in more players particularly with the potential for a gruelling Europa League campaign to stretch the squad further still.
4) Masuaku looks a real find
While Nordtveit and Tore were poor, new left back Arthur Masuaku looked the part on his debut.
The French left back was composed on the ball, quick and intelligent and always made himself available for a teammate.
He didn't get forward as much as fans' favourite Aaron Cresswell - who is out for four months through injury - but that will come with time.
Real promise of an exciting partnership between him and Payet on that left-hand side.
5) Valencia is the new Modibo Maiga
Valencia put a real shift in for West Ham at Stamford Bridge even if he didn't have the greatest of games on the ball. He continually gives away possession and didn't have a shot in anger.
But then the same could be said of Andy Carroll yet Valencia is the new scapegoat for the Hammers. He has been linked with a move away from East London and it would be best for all parties if his future was resolved swiftly.
In the meantime the longer the wait goes on for a quality performance and a goal from Valencia the worse the situation will get. Sofiane Feghouli and Payet will surely replace him next time out.