Jamie Vardy helped hand Ruud van Nistelrooy the perfect start as new Leicester boss – and pushed Julen Lopetegui closer to the brink at West Ham.
Striker Vardy pounced after just 98 seconds in Van Nistelrooy’s first game in charge, before Bilal El Khannouss and Patson Daka struck to seal victory for the hosts.
The Foxes moved up to 15th in the Premier League, two points behind the Hammers, but lived dangerously and needed goalkeeper Mads Hermansen to frustrate the visitors with a string of fine saves.
Niclas Fullkrug nodded home a consolation for the visitors in stoppage time.
But the pressure will remain on boss Lopetegui as he struggles to find a solution for success with the Hammers.
With just three wins from their last 12 top-flight games, Hammers fans vented their anger at the manager, but Lopetegui claimed not to have heard.
“I am a coach, I’m not aware of what happened around me,” he said. “I think we had a good match talking about football but talking about the score, no.
“We have to improve to be more effective in the opposite box and improve our consistency. I’m sure we are able to achieve this in the next challenge.
“There are a lot of matches in front of us and a lot of points, a lot of things which will happen. I believe in these players.”
Van Nistelrooy, who was appointed on Friday to replace Steve Cooper, has said he was not a romantic manager who will put style in front of results.
But the King Power Stadium will soon fall in love with the Dutchman if he continues to bring out the Foxes’ fighting spirit.
They relied on a gritty display against the Hammers, but also owed much to the wastefulness of the visitors.
Danny Ings hit the post with a close-range header, Jarrod Bowen spurned several chances, while Leicester defender Conor Coady cleared off the line from Crysencio Summerville.
After Vardy’s second-minute opener – although the Foxes needed to wait over two minutes for the video assistant referee (VAR) to rule the striker onside after he raced on to El Khannouss’ ball – keeper Lukasz Fabianski denied the veteran forward again, before the Hammers took control.
After Ings hit the woodwork, Bowen was twice denied by the excellent Hermansen.
The Hammers thought they had levelled after the break when Hermansen punched the ball into his own net as he tried to deal with a hanging ball, but Tomas Soucek was ruled to have fouled the goalkeeper in the build-up.
Almost immediately, Leicester broke and grabbed a crucial second in the 61st minute when Moroccan El Khannouss found the corner from Kasey McAteer’s pass for his first league goal.
Fabianski’s fine save stopped Wilfred Ndidi from adding a third, before Coady kept out Summerville’s bundled effort to keep his side in control.
Bobby de Cordova-Reid had another late Foxes strike ruled out for offside by VAR, but Daka wrapped up a dream night for Van Nistelrooy when he broke away in the 90th minute and rifled high into the net.
Fullkrug’s headed finish from Summerville’s corner was his first Hammers goal, but mattered little to the outcome as his side slipped to a disappointing seventh defeat in 14 league games.