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 have vented their frustration at the manager.
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 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.
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.
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.
Leicester show spirited response after Brentford bashing
Van Nistelrooy had just two days with his Leicester players before facing West Ham, but managed to transform them after a six-match winless run.
They led a charmed life at times, especially in the first half, but demonstrated the fight and fire needed to steer them away from the relegation places.
Van Nistelrooy watched from the stands on Saturday as the Foxes were dismantled 4-1 by Brentford, barely laying a glove on the hosts in their worst performance of the season.
But having taken training for the first time on Sunday, the Dutchman was delighted as Leicester’s response was full of endeavour and enterprise.
Foxes fans needed to see their team play for the shirt, with their commitment questioned by the travelling support at Brentford. There was no doubt this time.
Leicester’s unity has been one of the foundations of their success in the last decade and on Tuesday there were glimpses it could return.
