Manchester United's mini revival was ended by West Ham as they fell to a 2-0 defeat at the London Stadium.
Ole Gunnar Solskjaer's men had won back-to-back matches in all competitions heading into Monday's (AEST) Premier League clash but were beaten by goals from Andriy Yarmolenko and Aaron Cresswell late in both halves.
Yarmolenko scored the breakthrough goal 44 minutes in and Cresswell converted a free-kick six minutes from time to kill off United, who ended the match without a recognised striker after losing Marcus Rashford to injury.
Victory for the visitors would have lifted them into third place but it is West Ham who leap up the table, Manuel Pellegrini's men moving into the top four thanks to their third win of the season.
The sides managed just six shots between them in the first half - only one Premier League game has seen fewer in the opening 45 minutes this season - but West Ham found a way through from one of them.
Felipe Anderson played a first-time pass into the path of Yarmolenko, who took a touch and rifled the ball into the bottom-left corner of David de Gea's goal.
United continued to look disjointed in the opening 15 minutes of the second half and were further blunted in attack when Rashford was forced off in the 61st minute.
The visitors did come close to a leveller with 68 minutes on the clock, though, Harry Maguire seeing a low shot saved by Lukasz Fabianski after being teed up by Scott McTominay.
But they were punished for failing to take their only real opportunity of the match as Cresswell curled in a free-kick late on to seal the win.
What does it mean? Shot-shy United lacking options
Somewhat forced by injuries to key men, Solskjaer named an unchanged starting line-up in the Premier League for the second time this season - something United did not manage a single time in 2018-19.
Mason Greenwood, the match-winner against Astana, missed out through illness and Rashford's hamstring injury will cause further problems for Solskjaer.
For a side that has spent so heavily in recent years, they played the final half an hour of this match without a recognised striker on the field.
Felipe Anderson shows great awareness
Yarmolenko's movement, drifting from the right-hand side into the middle, caught out Maguire and United's other defenders.
Felipe Anderson's vision made the opening goal possible, the Brazil midfielder setting up his teammate to make it nine goals and six assists since the start of last season.
Rotten day for Rashford
In the prolonged absence of Anthony Martial, it has been left to Rashford to lead the line for United. In a fixture in which he tends to perform well, Rashford struggled to get involved and hobbled off on the hour having touched the ball only 24 times.
Both sides are in EFL Cup action on Thursday (AEST), with United hosting Rochdale and West Ham travelling to Oxford United.
Solskjaer's side then welcome Arsenal to Old Trafford on October 1, while the Irons face Bournemouth on the south coast next Sunday.