Chelsea's bid to retain the English Premier League title faltered again. West Ham handed the Blues their fourth loss of the season on Saturday by 1-0.
Chelsea remained 11 points behind leader Manchester City, which faces second-place Manchester United on Sunday.
"To talk about a title race after a defeat is a bit strange," Chelsea coach Antonio Conte said. "When you have this start it's impossible to think you are in the title race."
Marko Arnautovic's early strike was backed up by a resilient defensive display that ended an eight-game winless run for the hosts, and gave new manager David Moyes a first victory.
Third-place Chelsea will be looking over its shoulder after Tottenham thrashed Stoke 5-1 to win for the first time in five league games.
Burnley stayed level on points with Spurs as it beat 10-man Watford 1-0.
Also, Swansea rose off the bottom of the league after its first win in two months, switching with Crystal Palace, which blew a win when Christian Benteke missed a late penalty shot.
Here's a look at the league action:
West Ham's opening intensity was rewarded after six minutes when Arnautovic applied a fitting finish to a flowing move.
From then on West Ham retreated, often defending with all 11 players inside its own third of the pitch at the Olympic Stadium, with the tactic limiting Chelsea to very few opportunities.
"A really good start to the game by us and then we got a goal, which was a really well worked goal, and then it was a completely disciplined, organized performance," said Moyes, who replaced Slaven Bilic in early November.
West Ham remains in the relegation zone but the win put them level on points with 17th-place West Brom, which lost at Swansea 1-0.
For the second time this season, Chelsea allowed an opponent to end a long winless run.
West Ham hadn't won in eight league games.
Crystal Palace lost its first seven games until Chelsea visited in October.
"When you lose against Crystal Palace at the bottom of the table and now to lose again, against West Ham — that at this moment is in a bad position in the table — if you lose points in these games it means you are not in the title race," Conte said.
Tottenham became the first side in league history to win four consecutive games against the same opponent by four goals after it thrashed Stoke 5-1.
Harry Kane found the net twice, Son Heung-min and Christian Eriksen also scored, and Ryan Shawcross put the ball into both goals.
The only consolation for Stoke was that it scored. Its last three defeats to Tottenham were all by 4-0.
Crystal Palace manager Roy Hodgson was left explaining himself to fans after Benteke wasted an opportunity to secure a precious win. His last-minute penalty was saved by Bournemouth goalkeeper Asmir Begovic.
Luka Milivojevic converted a first-half penalty but Benteke took responsibility for the late attempt, against all advice.
Hodgson denied he had a post-match altercation with a fan over the issue: "He was asking why Benteke had been told to take the penalty. I was telling him he hadn't. Benteke got hold of the ball. It was a unilateral decision, no one on our team was able to wrest the ball from him."
THREE IN A ROW
Leicester registered a third consecutive league win after beating Newcastle 3-2 in a thriller at St. James' Park.
Newcastle forward Ayoze Perez's own goal four minutes from the end lifted the Foxes to eighth in the table.
Newcastle has taken just one point from its last seven games, and is 16th, only two points above the drop zone.
Wilfried Bony lifted Swansea off the bottom of the table thanks to his late goal to beat West Bromwich Albion 1-0.
"I was around the box and knew I just needed one chance as the game was tight," Bony said. "I was tired and just waiting. I saw the ball dropping and thought that was it."
Burnley won the matchup between the top tier's "overachievers" in beating Watford 1-0. Scott Arfield scored after Marvin Zeegelaar was sent off.
Also, Steve Mounie scored twice as Huddersfield defeated Brighton 2-0.