Jean-Philippe Mateta scored twice to condemn West Ham boss Graham Potter to a first Premier League defeat as Crystal Palace won 2-0.
The French striker made it four goals in his last three matches as Oliver Glasner's Eagles secured back-to-back away victories.
The Hammers also had defender Konstantinos Mavropanos sent off towards the end of a miserable afternoon for Potter.
England head coach Thomas Tuchel was in attendance at the London Stadium, casting his eye over Palace pair Eberechi Eze and Marc Guehi among others.
After a scrappy first half, it took Palace just two minutes of the second half to take the lead through Mateta's 10th goal of the season.
Lacroix cleared the ball from his own penalty area towards Ismaila Sarr, who flicked it on to Eze.
Tuchel would have enjoyed the midfielder’s first-time ball, which sent Mateta racing towards goal.
With Hammers defender Max Kilman back-pedalling and leaving far too much space, Mateta’s low strike from the edge of the box beat an unsighted Fabianski.
West Ham's hopes of snatching something were ended when they were reduced to 10 men after Mavropanos was shown a second yellow card for a high boot on Mateta.
And three minutes from the end Fabianski brought Eddie Nketiah down in the area and Mateta dispatched the penalty to wrap up Palace's victory.
Emile Smith Rowe and Adama Traore struck in the second half as Fulham beat Leicester 2-0, inflicting a seventh successive Premier League defeat on the hosts.
The Foxes provided another solid first-half showing but ultimately paid the price for a lack of quality and failed to learn their lessons from their midweek second-half collapse to Crystal Palace in a similar showing in front of their own fans.
The hosts’ defensive fragility showed after the interval and they conceded early for the second time in the space of a week courtesy of Smith Rowe’s fourth goal of the campaign.
The hosts were split open from Raul Jimenez's long ball over the top which found Harry Wilson, he cleverly kept the ball in play and his delivery was nodded on by Sasa Lukic and into the path of Smith Rowe, who tapped into an empty net.
A hostile home atmosphere did not improve Leicester’s performance and the Cottagers ensured a return to winning ways as substituted Traore handed Ruud van Nistelrooy’s relegation-threatened team a seventh loss from his first 10 games in all competitions.
