Jesse Lingard continued his one-man crusade to get West Ham into the Champions League with two goals in a 3-2 win over Leicester.
The England midfielder took his goal tally to eight in nine appearances since joining on loan from Manchester United in January to help lift the Hammers back into the top four.
David Moyes' side held off a late Leicester fightback and are now just a point behind the third-placed Foxes, and still on course to gatecrash Europe's elite next season.
Leicester's cause was not helped by a reported Covid-19 breach by some of their players, with a spokesman saying: "Those involved have apologised for their poor judgement. Our response to the matter will be concluded internally."
The first half an hour at the London Stadium would not exactly have had the European giants quaking in their boots, though.
But a moment of quality from the in-form Lingard, in front of England boss Gareth Southgate, put West Ham ahead.
Right-back Vladimir Coufal cut the ball back to the Lingard, who sent a precise volley past Kasper Schmeichel from the edge of the area.
Lingard struck again before half-time when the Leicester defence was caught out by a long ball from Issa Diop.
Jarrod Bowen stayed just onside as he raced towards goal, and as Schmeichel came out the winger squared for Lingard to tap into an empty net.
Lingard cut the ball back to Tomas Soucek, who played it on to Bowen for a simple finish from eight yards.
But West Ham have found 3-0 leads hard to hold onto in recent matches, having been pegged back to 3-3 by Arsenal and clung on for a 3-2 win at Wolves on Monday.
Diop thought he had made it four after 55 minutes but he was offside when he headed in Lingard's cross at the far post.
Instead the jitters threatened to set in again when Masuaku lost possession and Iheanacho lashed home.
Ricardo Pereira should have halved the deficit when he was played in by Youri Tielemans but Lukasz Fabianski thwarted the full-back.
Iheanacho did grab a second when he prodded in Marc Albrighton's cross at the start of six minutes of stoppage time.
Wesley Fofana then headed a last-gasp chance wide as West Ham held on to inflict only a second away defeat of the season on the Foxes, and strengthen their unlikely bid for a place at Europe's top table.