London - Chelsea dropped their first points of the season on Sunday as West Ham held Maurizio Sarri's team to a 0-0 draw to leave Liverpool out on their own at the top of the Premier League.
Chelsea had won all five of their league matches before the weekend, going toe to toe with Liverpool, who beat Southampton on Saturday to make it six wins out of six.
The visitors had 72 percent possession at the London Stadium but failed to create many clear-cut chances and had to deal with West Ham's constant threat on the break.
Sarri bemoaned his side's failure to kill the game off and said West Ham - who lost their first four matches of the season - were tough opponents.
"In my statistics we had seven opportunities against three," he said. "I knew that West Ham is a very good team. I don't know why they lost their first four matches in the Premier League."
"It's impossible to win every match," he added. "It's OK, one point today."
Olivier Giroud won his battle with Alvaro Morata for a starting spot up front for Chelsea, keeping his place for the second Premier League match in succession.
But Marko Arnautovic, West Ham's leading goalscorer this season, missed out after failing to recover from an injury he sustained in the victory against Everton last week.
Chelsea hogged the ball in the first half but West Ham were dangerous when they were able to break out, Michail Antonio proving a real handful.
After a cagey opening spell, Chelsea established control but the home side could have taken a lead against the run of play just before the half hour.
Felipe Anderson was quick to seize on a loose ball and played in Antonio, who blasted over with his left foot.
That chance breathed new life into the home crowd and the players and Antonio drew a smart save from Kepa Arrizabalaga in the West Ham goal just two minutes later after a fine run from Andriy Yarmolenko.
As the sun came out at the London Stadium, Chelsea again established control and nearly took the lead when N'Golo Kante headed wide.
The match fell into a similar pattern in the second half, Chelsea searching for openings around the West Ham box but Felipe Anderson and Yarmolenko looked dangerous when the home side broke forward.
The home side dealt well with the threat of Willian and Eden Hazard and Giroud - picked for his more physical threat - struggled to make a big impression on the game.
The Frenchman was replaced 20 minutes into the second half by Morata, who went close to breaking the deadlock moments after coming on only to see Lukasz Fabianski pull off a stunning stop from close range.
But with about 13 minutes to go West Ham had a wonderful chance to win the match, when the unmarked Yarmolenko headed just wide at the far post after a cross by Robert Snodgrass.
Fabianski pulled off another fine save as the clock ticked into injury time, diving to his left to deny substitute Ross Barkley and Willian blazed wide as Chelsea applied intense late pressure.
West Ham manager Manuel Pellegrini has managed to stop the rot with four points from the past two matches.
"When you have such clear chances against big teams you must score one of them," he said.
"And we had three clear chances before they created one chance but you must score."