The Blues have been in patchy form of late but begin the weekend level on points with fourth-placed Arsenal, while West Ham have been even more inconsistent than their hosts but remain in the hunt for a top-half finish.
The Italian seems to perpetually be one bad result away from the suggestion of the sack, even though victory on Monday night would be enough to lift the Blues into the Champions League places once again.
Sarri could justifiably feel aggrieved at some of the treatment he has received; Chelsea are six points better off than at the same stage of last season, reached the final of the EFL Cup and remain in the Europa League latter stages.
Many of the performances have not sufficed for the fans, though, even when the result has gone their way - as was the case last weekend when they needed two late goals to rescue a controversial victory over Cardiff City in South Wales.
Things were more straightforward in midweek as Chelsea cruised past Brighton & Hove Albion, although the performances of Callum Hudson-Odoi and Ruben Loftus-Cheek in that match will have only further convinced some of the fans that Sarri has got many of his decisions wrong at the helm so far.
That win over the Seagulls made it nine wins from their last 11 matches at Stamford Bridge across all competitions, while they have been beaten at home just once all season in the league.
The Blues also boast the joint-best defensive home record in the league this season, keeping seven clean sheets in their last 10 top-flight outings at the Bridge and conceding more than one goal in a game on only two occasions all term.
Statistics have not been enough to appease fans, though, and Sarri's job could well rest on a season-defining run coming up that sees Chelsea face this London derby and then both legs of their Europa League quarter-final either side of a trip to Anfield next weekend.
A return to the Champions League remains the goal next season, and Chelsea do still have two potential routes to achieve that, but Monday night represents a golden opportunity to steal a march on their domestic rivals with neither Tottenham Hotspur nor Manchester United in action.
The Blues could even sit as high as third come the final whistle of this match should Everton do them a favour against Arsenal on Sunday, but anything less than victory over their London rivals will see the pressure pile back on Sarri.
Recent Premier League form: WWDLWW
Recent form (all competitions): WDWLWW
If Chelsea fans feel like their form has been inconsistent, they should only look over to West Ham for comparison.
The Hammers have alternated between wins and defeats in their last six matches, which in fairness is at least an improvement on the five-game winless streak which preceded it.
Should that pattern continue on Monday night then West Ham will be celebrating a London derby victory that could be enough to lift them back into the top half of the table, depending on what happens during Everton's match with Arsenal on Sunday.
The trend within the pattern has been easy to see; when West Ham score, they do not lose - last doing so way back in August - but when they fail to find the back of the net they do lose, coming back empty handed from the last 10 league games in which they have drawn a blank.
Incidentally, the last time West Ham did fail to score and still come away with a point was in the reverse fixture against Chelsea at the London Stadium in September, but with their next four matches coming against members of the current top seven they will need to find their scoring boots more often.
Getting Marko Arnautovic back amongst the goals could be the difference in the closing weeks of the season, then, with the Austrian having failed to score a single goal since drawing the wrath of the West Ham fans with his desire to leave in January.
Indeed, since January 12 West Ham have scored only three goals while Arnautovic has been on the pitch compared to 11 without. Manuel Pellegrini has nonetheless asked the fans to ease up on the forward, who was such an influential figure for the team during the first half of the campaign.
With just five points separating the Irons from seventh place the prospect of Europe next season is not yet out of the question, although to do it they will need to significantly improve their away form having won none and lost six of their last seven outings on the road.
A return of just one away point from the last 18 available - and one goal, for that matter - is far from ideal at any stage of the season, but particularly when West Ham's next three away games come at Chelsea, Manchester United and Tottenham Hotspur.
It is a mercurial West Ham team that contains the quality to cause any side problems, though, and if they can frustrate an already-unhappy home crowd on Monday night then they could well upset the form book.
Recent form: WLWLWL
Loftus-Cheek has seized his chance in the past two games and may be hopeful of starting again should he overcome the hamstring issue which forced him off against Brighton.
Sarri has to strike a balance between fielding a strong side and rotating with the Europa League first leg coming up on Thursday night, although he is likely to see the Slavia Prague tie as a better chance to rest his key players.
Chelsea possible starting lineup:
Kepa; Azpilicueta, Rudiger, Luiz, Alonso; Kante, Jorginho, Barkley; Hudson-Odoi, Giroud, Hazard
West Ham possible starting lineup:
Fabianski; Zabaleta, Diop, Ogbonna, Cresswell; Antonio, Noble, Rice, Lanzini, Anderson; Hernandez
Head To Head
West Ham are unbeaten in their last three meetings with Chelsea and could go four for the first time since March 2000.
The Hammers have not won at Stamford Bridge since September 2002, though, when Paolo Di Canio scored twice in a 3-2 victory.
We say: Chelsea 2-0 West Ham
Chelsea were much improved against Brighton last time out and have been in decent form at home this season, whereas West Ham's recent record on the road is poor. Chelsea cannot afford to drop points with two of their main rivals not playing, and we are backing them to come away with the win.