Those in any doubt as to how a big transfer fee guarantees you nothing in football only had to look here at the desolate, isolated figure of Chelsea’s Ukrainian substitute Mykhailo Mudryk. Signed for almost £90m from under the noses of Arsenal last January, the winger has thus far made seven Premier League starts and scored precisely no goals. On as a half-time substitute here, he was wretched and, in some ways, the stumbling confused embodiment of Chelsea’s stumbling confused transfer policy.

Plenty more Chelsea money has been spent since that big transfer, of course, and in Mauricio Pochettino, Mudryk already finds himself playing for his third manager at the London club.

And so to the latest shining Chelsea jewel Moises Caicedo. Snatched last week from the doorstep of Liverpool for £115m, the former Brighton midfielder was not introduced until the hour mark, by which time his new team-mates were behind for the second time in the game. There was plenty of time for the 21-year-old to make his mark, especially when West Ham were reduced to ten men by the sending off of Nayef Aguerd. But Caicedo in the middle looked almost as lost as Mudryk did out on the left and when West Ham pushed on in added time, the Ecuadorian about whom so much fuss has been made lunged in on Emerson to concede a penalty from which Lucas Paqueta was able to seal the game.

There had been plenty of noise around Paqueta himself before this game after it emerged the Brazilian is being investigated by the FA for suspicious betting patterns. There was an element of surprise that he was even selected for the game by West Ham manager David Moyes.

But ultimately this was not Paqueta’s story. West Ham were gutsy and energetic and committed. They were outplayed by Chelsea for long periods, though, and when Pochettino and his players look in the mirror for reasons for this defeat this evening it will be their own failings staring back at them.

Lucas Paqueta scored from the penalty spot in the second half stoppage time to seal a memorable 3-1 victory for West Ham

Nayef Aguerd gave West Ham the perfect start by rising above Conor Gallagher to head in James Ward-Prowse’s corner

Carney Chukwuemeka brought Chelsea level with the youngster curling an effort beyond the dive of Alphonse Areola

Having overcome the blow of an early headed goal by Aguerd, Chelsea had equalised through Carney Chukwuemeka and dominated the game for much of the first half. But when another big signing Enzo Fernandez – a record signing at £107m back in January – saw a penalty saved by Alphonse Areola four minutes before half-time their fortunes headed south. West Ham began the second half the stronger and when Michail Antonio scored a superb second goal for them in the 54th minute they assumed the look of a team in no mood to surrender.

Moyes deserves credit for this. His own pre-season hasn’t been easy. Having lost Declan Rice to Arsenal, his own big signing James Ward-Prowse was able to deliver a corner for the first goal and was impressive in patches. Late in the game another new arrival, forward Edson Alvarez, also came on. It still feels as though there will be difficult times ahead for Moyes and his team but that only makes a day like today one to savour even more.

Early on West Ham were the better side. Indeed Chelsea began this game as they had the first of their Premier League season against Liverpool – slowly. They were behind early at Stamford Bridge and suffered the same fate here. This time they couldn’t say they hadn’t been warned.

West Ham’s first corner of the game had been taken by Ward-Prowse in the fifth minute and almost led to a goal as Kurt Zouma headed down and Jarrod Bowen was denied on the volley by goalkeeper Robert Sanchez. The next delivery two minutes later was similar in its delivery, curled out from the right to the far post. This time, having pushed Conor Gallagher out of the way, West Ham defender Aguerd was free to head down and in to the corner. On replays, Aguerd’s shove on Gallagher looked illegal but without doubt the Chelsea player should also have been stronger. Aguerd’s physical approach to the game was to cost him later on.

Ahead so early, West Ham had an opportunity to take a hold of the game. Chelsea at this stage were not cohesive. But it wasn’t long before the balance of possession and territory began to shift.

In the Chelsea midfield Fernandez began to see more of the ball and in turn the supply to the excellent Raheem Sterling started to cause West Ham all manner of problems.

As Chelsea came in to the game, Nicolas Jackson headed over before a Gallagher shot was parried by Areola. Over time the threat only grew, however, and when the equaliser arrived it was a very good goal indeed.

First Jackson caused West Ham a problem by making inroads on the left side and when the ball was only half cleared Chukwuemeka created an opportunity and as a result a goal for himself. His first touch to control the clearance in the penalty area was good and then trick he then pulled on Tomas Soucek to send him the wrong way and off balance was terrific. Having opened up space for himself the 19-year-old then had to take advantage and he did this by whipping a right foot shot wide of Areola with pace in to the far corner.

It was a lovely Chelsea goal and one that announced them, at that stage, as the dominant force in the contest.

Chukwuemeka celebrated the first goal of his senior career as Chelsea’s pressure on the West Ham goal finally paid dividends

Enzo Fernandez saw his penalty saved by Areola after Tomas Soucek had fouled Raheem Sterling on the edge of the box

Michail Antonio drilled West Ham back ahead in the second half by drilling an effort into the bottom corner of the Chelsea net

Aguerd was shown a second yellow card after the West Ham defender fouled Nicolas Jackson with a reckless sliding tackle

West Ham were forced to survive the final 30 minutes of the match against Chelsea with 10-men following Aguerd’s dismissal

West Ham tried to reply with a low Paqueta shot that grazed the post but at the other end of the field Sterling’s influence was continuing to grow. He couldn’t quite a control a superb Fernandez pass in the 38th minute but soon after that he run towards the penalty area from the left side panicked Soucek in to a rash challenge and Chelsea had a penalty. A VAR check was required to make sure the tackle hasn’t started outside the penalty area – it looked from some angles as though it had – but it ultimately didn’t matter as Fernandez telegraphed his shot rather and West Ham’s goalkeeper dived to his right to parry with two hands.

A Chelsea lead at half-time would have felt significant, given the way it had started. But it wasn’t to be despite a fabulous Sterling run that took him 30 yards past four players and in to the penalty area. Ben Chilwell’s subsequent shot was blocked by a West Ham defender as the home team hang on a little.

Chelsea were in the ascendency and had been for half an hour. But the break did them few favours. They reappeared for the second half looking like a rather less confident team and within ten minutes they found themselves chasing the game once again.

Said Benrahma served Chelsea notice that West Ham were re-energised when he shot across goal in the 49th minute. Five minutes later Moyes’ team were back in front.

Antonio’s finish, low across goalkeeper Robert Sanchez, was struck true and with perfect accuracy as he collected Bowen’s through pass down the right side. But the way he brushed off Levi Colwill to take possession will have infuriated Pochettino as indeed will the manner in which Axel Disasi lost the ball in the middle of the field in the first place.

The Chelsea manager sent Caicedo on for his debut soon after that setback and the arrival from Brighton was soon volleying a shot over from the edge of the penalty area. Sterling also continued to look dangerous but it was the sending off of Aguerd with more than 20 minutes still to play that did most to suggest a second blue comeback of the afternoon may be on.

Certainly the last third of the game was played mostly in the West Ham half. Aguerd, booked in the first half for a tactical foul on Sterling, was sent off for a reckless lunge at Jackson and with that second yellow card West Ham’s presence as an attacking force in the game was pretty much snuffed out.

Not that Chelsea were exactly kicking the West Ham door down. One of Pochettino’s attacking moves had been to send on Mudryk for the injured Chukwuemeka at half time. But the Ukrainian’s troubles encapsulated in the 85th minute when he moved on to a deep Sterling cross in space only to volley his attempted shot back across field to his team-mate who by then was standing in an offside position.

Indeed by the time we entered the first of six added minutes it was West Ham who were pushing, substitute Pablo Fornals bringing a save with his right foot from goalkeeper Sanchez.

And two minutes late Caicedo capped a miserable Chelsea debut by bringing down Emerson in the penalty area. Paqueta slid in the penalty.

Mauricio Pochettino brought on £115million record signing Moises Caicedo but the midfielder gave away a late penatly

Paqueta ended a difficult personal week by scoring from the spot to secure West Ham’s first three points of the season

David Moyes’ side impressed in front of their fans at the London Stadium with Ward-Prowse producing two assists on debut

Pochettino suffered his first defeat at Chelsea manager with the Blues picking up one point from their opening two matches