Diego Costa scored a dramatic 89th minute winner to give Antonio Conte a winning start to his Chelsea career against West Ham.
Chelsea’s first goal under the Italian came just after half time as Eden Hazard smashed his penalty into the roof of the net.
However, despite being under the cosh for most of the second half, the Hammers equalised through James Collins.
But Costa popped up to give Conte a dream start to life in the Premier League.
Summer signing N’Golo Kante marked his first competitive Chelsea game with a third minute yellow card as both teams jostled for the upper hand.
West Ham had the best of the early possession but it was the Blues who had the first chance of note when Branislav Ivanovic drew a fantastic low save from Adrian.
There was controversy after 20 minutes when Oscar went to ground when Winston Reid stuck his arm out but it looked soft and referee Anthony Taylor dismissed the penalty claims.
Hazard was next to go close when he showed a clean pair or heels to Andre Ayew – who consequently went off injured – before firing a low shot just wide of the far post.
However, just after the break Hazard scored the first goal of Conte’s Premier League reign when Michail Antonio brought down Cesar Azpilicueta in the box, with the Belgian converting from 12 yards.
Willian forced another strong save from Adrian after 62 minutes before John Terry sent a free header over the bar from the resulting corner.
Costa was lucky not to see a second yellow card when he went in late on Adrian after the goalkeeper dallied on the ball inside his own six-yard area.
West Ham hadn’t had a shot on goal until the 76th minute when Collins thumped a left-footed half-volley past Thibaut Courtois to draw the sides level.
It was the Welshman’s ninth career goal and his fourth against Chelsea.
Michy Batshuayi came on for his Chelsea bow but it was Costa who made the telling contribution with a low, fierce shot that Adrian couldn’t get his palms to give Chelsea and Conte three important points.