Alexis Sanchez’s hat-trick condemned West Ham United to a resounding 5-1 defeat as Arsenal thrashed the Hammers at London Stadium.

Andy Carroll’s header was a mere consolation as goals from Mesut Ozil and Alex Oxlade-Chamberlain added to Sanchez's trio of strikes to deepen West Ham’s relegation worries.

With Slaven Bilic facing questions over his future, this heavy defeat will only add fuel to the fire surrounding his position as manager.

West Ham will look to lift themselves in time for the trip to Anfield to face high-flying Liverpool next week.

The Hammers made four changes from the side which drew 1-1 with Manchester United in their last Premier League outing as Winston Reid, Arthur Masuaku, Edimilson and Ashley Fletcher came in.

Fletcher’s start came after he scored the equaliser in West Ham’s 4-1 EFL Cup defeat against United at Old Trafford in midweek.

It was only the 21-year-old’s second league start since joining the club in the summer, with the other coming in August’s 3-1 defeat to Manchester City.

There was positive news on the injury front for the hosts as Carroll took his place on the bench to be involved in a league squad for the first time since the opening day.

Bilic’s men began the match just a point above the relegation zone and their form, which has seen them fail to win any of their last four, is in stark contrast to the Gunners.

Title chasing Arsenal arrived at London Stadium unbeaten in their last 10 league matches and knowing a win would take them up to second.

And Arsene Wenger’s side certainly started the brighter as Nacho Monreal’s surging runs from left-back caused West Ham a number of problems in wide areas.

The Spaniard found himself in space inside the box on three occasions inside the first 15 minutes but failed to pick out an Arsenal man with his cut back each time.

The faintest of touches from Winston Reid proved particularly telling as he prevented Monreal’s third cross presenting an Unmarked Sanchez tapping in from six yards.

Arsenal were in the ascendency, but it was the hosts who forced he first save of the game after 17 minutes as Dimitri Payet’s superb through ball dissected the Arsenal defence to send Manuel Lanzini clear.

The retreating Laurent Koscielny did superbly to force the Argentine wide and his left footed shot was routinely turned around his near post by Petr Cech.

Sanchez’s work rate had been keeping the West Ham defence honest throughout, and a momentary lapse in concentration gifted the Chilean the chance to create the opener.

Francois Coquelin charged down a languid pass out of defence from Angelo Ogbonna before Sanchez raced clear and nicked the ball beyond Reid.

With just Darren Randolph to beat, Sanchez selflessly squared for Ozil and the German duly tapped into the empty net for his eighth goal of the campaign.

After a relatively even opening the manner of the goal came as a bitter blow for the Hammers as they gave the league’s third most prolific side a scarcely deserved lead.

The visitors failed to build on their advantage and bar Sanchez’s run through the middle created little in the remainder of the half.

They were firmly in control of matter, however, and West Ham’s inability to muster a coherent argument going forward meant the Gunners' lead rarely looked threatened ahead of the interval.

A lively start to the second period saw Theo Walcott spurn two chances to increase West Ham’s woes as he headed over when unmarked from Ozil’s free kick and miscued a left footed chip.

The Hammers responded well and their most fluid move of the night almost gave Fletcher the chance to square the scores.

Payet was again at the heart of things, threading a through ball into Lanzini whose low cross was cut out by Koscielny just as Fletcher set himself to sweep home.

The youngster rounded off a spell of West Ham pressure as he sent a powerful drive just wide from 20 yards moments later.

Any hopes of West Ham mounting a comeback were kept alive with just over 20 minutes to play as Randolph made a superb double save to deny Aaron Ramsey and Ozil.

Again the danger came down the Arsenal left as Monreal made another burst into the West Ham box and pulled back for Ramsey.

Randolph denied the Welshman’s prodded effort with his legs and was back on his feet to block Ozil’s volleyed follow up.

He could do little to prevent Sanchez, undoubtedly the game’s outstanding player, putting the contest to bed in the 72nd minute though.

After picking the ball up some 25 yards from goal, Sanchez powered past Masuaku on the right channel and unleashed a fierce drive across goal and into the bottom corner.

With 10 minutes remaining Sanchez further stamped his name across the game after firing low past Randolph for his second.

Carroll gave the West Ham fans reason for optimism two minutes later as he reacted quickest to head home after Payet’s free kick had come back off the bar.

There hope was short-lived though and Oxlade-Chamberlain curled a stunning strike from distance beyond the despairing Randolph to restore Arsenal’s three goal advantage.

The game was given a fitting conclusion with four minutes remaining as Sanchez completed his hat-trick with the most delightful of finishes.

This time Oxlade-Chamberlain played provider with the through ball which set Sanchez in on goal.

What followed was quite sublime as Sanchez sent Randolph to ground with step over and lifted a chip over the Hammers keeper to compound West Ham’s misery.

West Ham United: Randolph; Reid, Collins (Arbeloa 7), Ogbonna, Fernandes (Ayew 63) Obiang, Noble (C), Masuaku, Payet, Lanzini, Fletcher

Subs not used: Adrian, Nordtveit, Feghouli, Carroll, Zaza

Arsenal: Cech, Gabriel, Mustafi, Koscielny (C), Monreal, Xhaka, Coquelin, Walcott (Ramsey 66), Ozil, Oxlade-Chamberlain, Sanchez

Subs not used: Ospina, Gibbs, Perez, Holding, Iwobi, Elneny

Bookings: Coquelin (30 kicking ball away), Fletcher (58 foul on Koscielny), Reid (65 dissent), Kosceiolny (67 foul on Fletcher), Mustafi (82 foul on Ayew)

Referee: Craig Pawson

Attendance: 56,980