Monday, 15th August 2016
The Spanish international - who was already on a yellow before committing three further bookable offences, all of which referee Anthony Taylor ignored - struck the winning goal with seconds to spare after James Collins' 77th-minute strike looked to have rescued a point for the Hammers.
West Ham, missing the likes of Angelo Ogbonna, Manuel Lanzini and Aaron Cresswell also started without Dimitri Payet, who is still recovering from his Euro 16 exploits.
And despite enjoying the bulk of possession in the opening half hour, the Hammers failed to seriously test Thibaut Courtois until Collins recorded United's first effort on target with his goal, 13 minutes from time.
By that time the hosts had perhaps deservedly taken the lead through a 47th-minute Hazard penalty, conceded by Michail Antonio who inadvertently felled Cesar Azpilicueta inside the box.
The right winger, playing again at full back was rewarded by being instantly replaced by Sam Byram - and ignored by manager Slaven Bilic as he trudged dejectedly back to the visitors' dugout.
Thereafter Byram proved an able replacement for Antonio, playing on the opposite side to new signing Arthur Masuaku who was one of three players making their Premier League debuts in United's starting XI.
Havard Nordtveit and Andre Ayew also started for the first time although the latter's evening was cut short just 35 minutes in after he suffered a thigh strain, an injury that will be assessed tomorrow morning. Gokhan Tore made his debut from the bench as a replacement for the stricken Ayew.
Chelsea, despite looked in control after taking the lead were always susceptible to a sucker punch holding such a slender lead. And it was James Collins who delivered what appeared to be a knockout blow when he steered the ball through a cluster of bodies to draw West Ham level 13 minutes from time.
That was until Costa fired across Adrian from an acute angle to win all three points for the hosts with little more than a minute of normal time remaining. Controversially, because had referee Anthony Taylor applied the letter of the law correctly the Spaniard might have been dismissed twice before scoring his goal - and once more again thereafter!
Booked for dissent in the first half, Costa deliberately raked Adrian's shin in the second only for Taylor to simply award a free kick; the ugly challenge was quite possibly worthy of a straight red on its own.
Minutes later his attempt at simulation inside West Ham's penalty area also went unpunished, as did the removal of his shirt whilst celebrating the winning goal. Although they were poor tonight, it's fair to say the Hammers haven't had the best of luck with match officials at Stamford Bridge this calendar year.
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Adrian San Miguel Del Castillo
Almost conceded a goal when trying to dribble round Costa and could perhaps have done better with the winning goal.
Gave away a penalty and hauled off immediately as reward. But he shouldn't be playing at right back.
A tough place to make your Premier League bow, but Masuaku showed enough at the Bridge to offer Hammers fans hope going forward.
Did okay under pressure and rarely put a foot wrong.
Put in another good shift at the heart of defence and scored a beauty to give West Ham hope of salvaging a point.
An okay Premier League debut although his distribution was a little wayward at times.
Not really in the game at all, which was unusual for a player of Cheik's quality.
Probably not ther performance Noble was hoping to offer in front of watching England manager SAm Allardyce.
Like his strike partner the big man failed to muster a single shot on target.
The club record signing looked lively enough before a thigh strain ended his debut little more than half-an-hour in.
Put himself about as much as a wet paper bag can, but still completely ineffective.
Essentially chased shadows whilst not looking entirely match fit.
A decent performance from the youngster and one that left fans querying why he wasn't in the starting XI.
One wasted free kick was just about the sum of his efforts.
Referee: Anthony Taylor.
Man of the Match: James Collins.
West Ham United
Adrian San Miguel Del Castillo, Michail Antonio, Arthur Masuaku, Winston Reid, James Collins, Havard Nordtveit, Cheikhou Kouyate, Mark Noble, Andy Carroll, Andre Ayew, Enner Valencia.
Goals: James Collins 77 .
Booked: Michail Antonio James Collins 0 .
Sent Off: None sent off. .
Subs not used: .
Goals: Hazard (47), Costa (89).
Sent Off: None sent off..