Diego Costa scored a dramatic winner with one minute remaining to give Chelsea a 2-1 victory over West Ham in Antonio Conte's first Premier League match in charge.
Having had the better of a quiet first half at Stamford Bridge on Monday, Chelsea netted what they thought would be the game's only goal when Eden Hazard blasted home a 47th-minute penalty after Michail Antonio had fouled Cesar Azpilicueta.
But West Ham, who kept Dimitri Payet on the substitutes' bench until midway through the second half, saw defender James Collins stun the hosts with 13 minutes remaining - scoring with their first shot on target.
However, it was Costa - fortunate to still be on the pitch following a reckless lunge on goalkeeper Adrian - who had the last word with an impressive long-range winner.
Despite the late nature of their triumph, Chelsea - still unbeaten at home to West Ham in the Premier League since September 2002 - were deserving of the victory, with Conte celebrating wildly after the controversial Costa struck.
The Blues are back in action away to Watford on Saturday, while Slaven Bilic's men have a Europa League tie against Astra on Thursday.
Chelsea threatened first when Branislav Ivanovic combined with Oscar and forced Adrian into a smart save at his near post.
Conte and Oscar were then both demanding a penalty when the Brazilian dispossessed Mark Noble and charged into the box before going down as Winston Reid challenged, but referee Anthony Taylor waved away their claims.
Hazard and Costa both shot narrowly off target as the hosts looked most likely to make the breakthrough, while West Ham suffered a major blow with debutant and club-record signing Andre Ayew forced off due to a thigh injury.
Within 52 seconds of the restart, Chelsea were awarded a penalty when - moments after Adrian had denied Costa from close-range - Antonio rashly brought down Azpilicueta, with Hazard smashing the resulting spot-kick into the roof of the net.
Adrian got down well to keep out Willian as Conte's men attempted to put the result beyond doubt, while Bilic finally introduced Payet for the last 23 minutes with the visitors still seeking their first shot on target.
Costa - already on a booking - was extremely fortunate to avoid a red card for a lunge on Adrian, before West Ham grabbed a shock leveller.
Payet's corner had led to Cheikhou Kouyate having an effort blocked before Collins lashed home a magnificent left-footed finish from just inside the penalty area.
Conte threw on Pedro, Michy Batshuayi and Victor Moses in the closing stages and was ecstatic when his alterations paid dividends.
It was debutant Batshuayi's flick that picked out Costa more than 20 yards from goal, with the Spain striker finding the bottom corner to seal a memorable victory, sending Conte wild on the touchline.