West Ham inflicted more away-day pain on Manchester United on Sunday, beating Ole Gunnar Solskjaer's pedestrian team 2-0 at the London Stadium to underline the huge task the Norwegian faces.
Andriy Yarmolenko's goal shortly before half-time and a wonderful late Aaron Cresswell free-kick mean United have not won away from Old Trafford in any competition since March.
Manuel Pellegrini's West Ham are now unbeaten since a 5-0 drubbing by Manchester City in the first match of the season and the win lifted them into the top four ahead of the later matches on Sunday.
But it was a chastening day for Solskjaer's men, just a day after City came close to matching United's Premier League record for margin of victory -- 9-0 against Ipswich in 1995.
Missing Paul Pogba and Anthony Martial, the visitors were woefully short of creativity in midfield and toothless in attack.
United, who started the season by thumping Chelsea 4-0, have lost twice already in their opening six league games and are without an away win in any competition since their dramatic Champions League victory against Paris Saint-Germain.
Solskjaer tried to put a brave face on the defeat despite the sub-par performance, saying his team had failed to take their chances.
"We didn't create enough chances but we created big chances, some big moments that we didn't take and they scored," he said. "They didn't create too many either."
- Striker shortage -
The Norwegian admitted United were short of firepower up front, with Marcus Rashford limping off in the second half to compound his problems.
"This group want to do what we're trying to do in training," he said.
"It's key moments in games that can tip these games in our favour... but the attitude and desire is there. That's not the problem. It's the quality in our decision-making and sometimes in the execution."
Solskjaer played the same side that triumphed against Leicester last week while Pablo Fornals came in for the injured Manuel Lanzini for West Ham.
Both teams were cagey at the start of the match, with neither side able to create clear-cut chances.
West Ham looked the more inventive team when they broke forward while United looked ponderous in attack and lacking in ideas, with Rashford isolated up front.
An uneventful game was drifting towards a half-time stalemate when Felipe Anderson's neat chip set up Yarmolenko, who drove past David de Gea in the 44th minute to dent United's confidence.
United went close to an equaliser early in the second half as the rain came down in London, with Juan Mata missing from close range after an Andreas Pereira cross.
Already short of options up front and missing creators in midfield, they lost Rashford on the hour mark, replaced by the out-of-form Jesse Lingard.
Rashford's early departure will raise more questions about United's summer transfer business, when they failed to bring in a replacement for Romelu Lukaku.
West Ham went close to doubling their lead shortly afterwards but De Gea got down low to keep out an Anderson shot from a tight angle.
United upped the pressure and West Ham had goalkeeper Lukasz Fabianski to thank for keeping out a Harry Maguire strike from close range.
But West Ham continued to look more dangerous on the break and made United pay when Ashley Young brought down Mark Noble on the edge of the penalty area.
De Gea was a bystander as Cresswell curled a free-kick into the top right-hand corner to add to United's pain.
Pellegrini said his side deserved the win, adding: "I'm very happy about everything today and the way we played."
"It doesn't matter if we play here against United or against every big team," he added. "We must trust that we are able to beat them."