3 reasons why Chelsea lost 1-0 to West Ham United

Chelsea succumbed to a 1-0 defeat to London rivals West Ham United at Stamford Bridge in the Premier League.

The Blues were favourites to get back to winning ways in the league after losing to Manchester City last time. After Wednesday's draw against Valencia, Frank Lampard's side had their sights on the three points. But an out of sorts West Ham side came up with an upset in the London derby.

The first half was pretty even, but Chelsea had the majority of the chances. Reece James was impressive, and Olivier Giroud and Christian Pulisic failed to connect with his crosses. Tammy Abraham missed the game due to injury, and his absence was felt keenly.

West Ham started the second half strongly and took the lead early on. Aaron Cresswell bent a fine finish past Kepa Arrizabalaga to give his side the lead. Once ahead, West Ham did well to smother any opportunities Chelsea had. The Blues added pressure as the game progressed, but the Hammers held on to claim a vital win.

Chelsea stay fourth in the league, but the win gave West Ham a massive jump. They are now three points clear of the relegation zone. Here are the main reasons why Chelsea lost to the Hammers.

#3 Olivier Giroud rendered insignificant for Chelsea

Giroud failed to make his mark

Tammy Abraham has been the first-choice striker for Chelsea this season, and the youngster has done justice to his role. But he went off injured against Valencia on Wednesday which ruled him out of the West Ham game.

Lampard had the choice between Michy Batshuayi and Olivier Giroud, and he chose the latter. The Frenchman has a particular set of qualities, which include aerial ability and hold-up play. But he failed to impose neither on the game.

James put in a handful of crosses in the first half, but that was it for Giroud. One of them was a great chance, but he failed to judge the flight of the ball. Other than that he had little impact on the game overall. Lampard could look to Batshuayi for the coming games if Abraham fails to recover from his injury.

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#2 West Ham's defence and goalkeeper improve drastically

Martin had a solid debut

If one looked at the last few games, West Ham United were arguably the worst side in the league. One of the major reason for this was their defence. Since Lukasz Fabianski got injured, the Hammers have looked shaky at the back.

Roberto Jimenez was deputising in goal, and the Spaniard had a torrid time. The defence in front of him was not encouraging either, but all that changed against Chelsea. Manuel Pellegrini gave goalkeeper David Martin his West Ham debut, and the decision paid off. The game was memorable for the 33-year-old, and he got a well-earned clean sheet.

Both Angelo Ogbonna and Fabian Balbuena were solid as well. All members of the back four impressed and Cresswell got the goal to boot. Pellegrini will be pleased with his side's defensive display. Chelsea found it tougher than expected, and West Ham shored up their goal well in the closing stages to get the points.

#3 Chelsea were not clinical in front of goal

Pulisic was Chelsea's best threat

Aside from the scoreline of the game, Chelsea dominated in all the other numbers. They took 19 shots in the game compared to just 5 from West Ham United. Fourteen of those shots were in the box, and just as many were on target for the Blues.

Chelsea completed almost twice the passes of West Ham and had 65% possession. But they were not clinical and could not finish their chances. Too many of those attempts were off the mark. According to Understat Chelsea's xG total was 2.73, while their opponents had 1.12 xG.

The difference is huge, but West Ham came up with a brilliant finish and Chelsea could not. Lampard will need to address this issue as Chelsea have impressed against lower teams with deep defensive lines. Wednesday's game against Aston Villa will present the perfect opportunity to do so.