Tomas Soucek of West Ham United celebrates Photo: PHOTOSPORT
Misfiring Arsenal spurned the opportunity to reclaim first place in the Premier League as they lost 2-0 to spirited fellow Londoners West Ham United at the Emirates.
West Ham only had three efforts on target but Tomas Soucek gave them a halftime lead before former Arsenal defender Konstantinos Mavropanos extended the advantage after the break.
Arsenal had more than twice as many chances but failed to take any as the visitors defended gamely.
Second-placed Arsenal remain on 40 points, two behind Liverpool who beat Burnley 2-0 on Tuesday.
"This is a very disappointing night for us," Arsenal manager Mikel Arteta said. "We have to put the ball in (the net) and win it (the game)."
The win leaves West Ham in sixth place on 33 points and marked a landmark night for their manager David Moyes who had never won at Arsenal in the league in 22 attempts.
Brighton & Hove Albion moved into eighth place with a 4-2 mauling of Tottenham Hotspur to end a superb year under Italian manager Roberto De Zerbi.
The south-coast club may not have the spending power of the teams around them, and regularly sell key players to their rivals, but they have continued on an upward trajectory after qualifying for Europe for the first time last season.
After his side's first win in four Premier League games, De Zerbi, now one of the most respected coaches in Europe, was at pains to point out the size of the club's achievements.
"I am really lucky to be this coach of this team with these players. I am very pleased with the passion they have, they have everything," he said.
"You can't forget we are Brighton. Sometimes they forget we are Brighton. We are not Manchester United, Manchester City, Newcastle or Arsenal, we are still Brighton.
"The other eight or nine big teams in the Premier League they do not sell their big players."
Brighton have 30 points, while Tottenham are fifth on 36 points.
-Reuters