The Blues were thwarted by an industrious Crystal Palace side as they huffed and puffed to a goalless draw, whilst the Hammers were hammered at the Stadium of Light, losing 3-0 to newly-promoted Sunderland.
For Graham Potter to still defend his players in the wake of that defeat was a surprise, for they were well beaten, and the East London outfit will certainly need to be at their best if they want to get anything from the game against the Club World Cup winners.
West Ham's home form under Potter doesn't bode well, however, as two wins, three draws and four losses have seen the Irons picking up just nine points from the manager's previous nine home games.
Graham Potter could make unwanted West Ham history
No Hammers manager has ever not got at least 10 points from their first 10 home games in the job, with Alan Curbishley and Avram Grant's 10 being the lowest accrued to date.
Potter was pushed out at Chelsea after less than seven months in the job, and despite there being widespread optimism when he signed on at the London Stadium, he is approaching his seventh month at West Ham with the jury very much out on what actual improvements, if any, have been made during his brief tenure.
At present, his win percentage after 20 Premier League games in charge is a lowly 25%. To give even more perspective, Manuel Pellegrini's 21 English top-flight games saw him end with a 28.6% win rate, whilst Julen Lopetegui's 22-match reign in the league gave him a 31.8% stat.
There's nothing to suggest that the Hammers board are going to react yet, but it's difficult to make a case for Potter being the right man when placed in the context above.
Hammers have recent edge over Chelsea
He may take heart in the fact that in the last 11 fixtures in all competitions between the two teams, the Hammers have won six, two have been drawn and just three have been won by Chelsea. In the Premier League, the balance is even more in West Ham's favour with their five wins in the last seven (D1, L1).
However, this is a fixture that the Blues enjoy given that they've beaten their opponents on no less than 32 previous occasions in the Premier League. Only their record against Tottenham (37 wins) is better.
Were they to triumph in East London again, it would be the ninth time that West Ham have lost their opening two games in a Premier League season, equalling the current worst record in that regard held by Southampton.
New Hammers keeper Mads Hermansen won't want to dwell on the events of the opening weekend either, with that defeat meaning he still has just one clean sheet from his last 28 matches.
That's the joint-second lowest rate (3.6%) of any keeper that's played more than 20 games in Premier League history. Only Wes Foderingham (3.3%) has a worse stat - and he is one of the backup keepers at West Ham.
Jarrod Bowen key for the hosts
Chelsea haven't gone two matches from the start of the season without scoring since 1995/96, so Hermansen and his defence have their work cut out.
Hammers supporters still trying to digest the strength of that Sunderland defeat will surely be pinning all of their hopes on talisman Jarrod Bowen, who has scored three goals in his last four London derby appearances.
The responsibility can't all be on the striker's shoulders, however, with each player needing to do their bit against a team that will still be smarting from their own inability to secure a win on opening day, despite having 19 shots against the Eagles.
That match also saw Chelsea complete the joint-most passes of any side on the opening day (510, the same as Manchester City), so there may have to be an acceptance by Potter and his staff that the hosts need to play a counter-attacking game in order to earn themselves at least a draw.
Allowing an opponent the lion's share of possession won't come easily to a manager who likes his teams to dominate in that regard, though if the Hammers do try to stand toe-to-toe with the Blues, the visitors would appear to have better players, with respect, to execute their own game plan.
In this fixture last time out at the London Stadium, Chelsea romped to a 3-0 win, and a similar scoreline on Friday could well see Hammers fans calling for Potter to go the way of Lopetegui.
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