Chelsea slumped to a 2-3 defeat against West Ham at the London Stadium in the Premier League on Saturday afternoon.
After riding their luck in the midweek win against Watford, the Blues finally came undone by a spirited Hammers side who twice overturned a deficit to stun the league leaders.
The visitors took the lead in the 28th minute, with the timeless Thiago Silva diverting home a pinpoint Mason Mount corner in the 28th minute. A Manuel Lanzini penalty after a comedy of errors from the Pensioners drew the Irons level 12 minutes later, but it was to be short-lived with Mount firing true with a goal of the season contender on the stroke of half-time.
It was yet again a familiar tale for Tuchel at the break. Plenty of positives to take and Chelsea in the ascendancy, but one big negative in that Kai Havertz had to be withdrawn through a nasty knock that a short on the ground squad can ill-afford during a busy Yuletide schedule.
There was more bad news on the horizon, with a neatly crafted Hammers move concluding with Jarrod Bowen finishing low into the back of Edouard Mendy's net in minute 56. A freak Arthur Masuaku cross-cum-shot then caught Mendy out completely in the 87th minute.
In the end, an entertaining 90 minutes ended with the East Londoners taking all the spoils. Next up for the Blues is a trip to chilly St. Petersburg to face off against Zenit in the final Champions League group game. In the meantime, here are today's player ratings...
Edouard Mendy - 3/10
Not immediately apparent as to why he did not aim for Row Z rather than concede a penalty for West Ham's first. His shaky distribution did not inspire confidence thereafter. He may well feel he should have done better for the second, but the third is a given. His worst performance in a Chelsea shirt.
Andreas Christensen - 5/10
That the ball flew through his legs for said West Ham's second is rather typical of the Dane's situation at current. After a particularly excellent nine months or so in his career, he is looking a little complacent and distracted - perhaps unsurprising with all the noise surrounding his future, but little excuse for a drop off in performance levels.
Thiago Silva - 8/10
'O Monstro' can barely do no wrong at the moment. Followed up a lovely cushioned header into the back of the Hammers' net by preventing the ball going into his own with a superb goal-line clearance no more than one minute later. Will be personally disappointed to come undone slightly for Bowen's goal, but that should take nothing away from a fabulous footballer in his finest fettle of form going into the twilight of his career - news of a new contract cannot come quick enough.
Antonio Rüdiger - 5/10
If he met a worthy foe three days prior up against Emmanuel Dennis, today he met someone he could not handle. Jarrod Bowen had so much joy in the channel, and the German struggled to keep pace with his electric showing.
Reece James - 6/10
Manuel Lanzini goaded him following his converted penalty and that was probably the most noteworthy occurrence of his afternoon. Some nice deliveries as is par for the course, but not a lot to aim at even with the supposedly formidable Romelu Lukaku lurking in the area.
Jorginho - 5/10
By his lofty standards, this was a sloppy and nervy showing even beyond his selling short of Edouard Mendy for the Irons' goal. Seemed agitated from the off, earning an early yellow for dissent. Still, for the most part there was evidently increased control in the Chelsea engine room than there had been at Vicarage Road 65 hours earlier - a match the Italian had missed through injury.
Ruben Loftus-Cheek - 7/10
Guilty of being laboured and ponderous in possession recently, but it was noticeable that he was markedly improved in releasing the ball quicker and with more intent when driving forward today. A powerful and impactful demonstration of the unique traits he can bring to the Pensioners' midfield.
Marcos Alonso - 6/10 
Competent enough, particularly doing well to beat a targeted West Ham press. But it is no secret that the Blues are far less dynamic in the final third with the Spaniard than with former Leicester man Ben Chilwell.
Hakim Ziyech - 8/10 
The Moroccan livewire was an handful for the Hammers, drifting between the lines with an energetic elegance and constantly looking for the most progressive play available. His role in Chelsea's second was exquisite, shaking free of his marker with deft poise before pinging across a laser-guided switch on to the side-foot of teammate Mount. He can frustrate at times when his ideas don't come off, but when they do it really is magical from 'The Wizard' - and you get the sense there are a lot more tricks up his sleeve to come.
Mason Mount - 9/10
Large swathes of the first period were the Mason Mount show, with Chelsea's talisman quite visibly back to full speed and firing on all cylinders with a velvety touch and impactful ball carries. Apt, then, that such a display was capped off with the young Englishman rifling a sumptuous volley past Lukasz Fabianski following an equally sumptuous Chelsea move. On song, there is little surprise the Blues' winning percentage is a damn sight higher with him than without - even if that was not to be the case today.
Kai Havertz - 7/10 
After his star turn against Watford, the German was afforded less space by a tight unit of West Ham's giant centre backs - one of which a familiar foe in former teammate Kurt Zouma. It was a shame a clash between the two brought an early end to the afternoon for the former Leverkusen man, who was definitely growing into proceedings and increasingly fashioning some room to work with.
Romelu Lukaku - 4/10 
Chelsea's record transfer signing was only fit enough to start on the bench again, but Thomas Tuchel's best laid plans went awry when the Belgian had to be called into action early on account of the aforementioned injury to Kai Havertz. Played like he was not fully fit, either. Not nearly effective enough an outlet as the man he replaced and was quite clearly off the pace.
Callum Hudson-Odoi - 4/10 
Saw plenty of the ball in his time on the field, but he dallied in possession on one occasion too many when the prospect of a killer pass presented itself. A real lack of cutting edge at one end and caught out during his defensive duties at the other.
Christian Pulisic - N/A