West Ham’s unbeaten European record was reduced to ruins in Athens as they crashed to a 2-1 defeat at Olympiacos.
The Hammers came a cropper in the shadow of the Acropolis as they suffered a first loss in UEFA competitions in 18 matches.
David Moyes, who led his side to the Europa Conference League title last season, made seven changes for their Europa League Group A clash in the Greek capital.
But his selection backfired as a soft goal from Olympiacos captain Kostas Fortounis and an own goal from stand-in Hammers skipper Angelo Ogbonna brought their undefeated run to a halt despite Lucas Paqueta’s late reply.
A hostile reception for West Ham was guaranteed at the Georgios Karaiskakis Stadium, with Olympiacos even issuing a warning to their supporters not to throw missiles or target players with laser pens.
That plea came after their match against fierce rivals Panathinaikos on Sunday had to be abandoned when a visiting player was hit by a firework hurled from the crowd.
With tensions high in Athens – Panathinaikos were also playing at home a few miles away – around 1,600 West Ham fans were bussed in from the city centre to the ground under a police escort to avoid any potential trouble.
The local ‘ultras’ did not disappoint, with a huge banner reading “tonight you dine in hell” welcoming the visitors on to the pitch amid a cauldron of noise.
Moyes would certainly have found West Ham’s first-half display hard to stomach.
The hosts took the lead in the 34th minute when Fortounis turned away from Emerson Palmieri, James Ward-Prowse and Pablo Fornals far too easily, 25 yards out.
Fortounis launched an old-fashioned toe poke from the edge of the box which flew past the flat-footed Alphonse Areola in the West Ham goal.
On the stroke of half-time the Hammers found themselves two behind when Ogbonna suffered his own personal Greek tragedy.
The Italian veteran stuck out a foot to block a cross from Brazilian full-back Rodinei, only to help it past Areola into his own net.
Moyes will have been having a bad case of deja vu; his ill-fated spell in charge of Manchester United included a 2-0 defeat at the same stadium in 2014.
West Ham did at least come out in the second half with more purpose, but a low cross from Emerson was scooped over the crossbar by Danny Ings.
Moyes made a triple substitution before the hour mark with Paqueta, Jarrod Bowen and Michail Antonio entering the fray.
Paqueta halved the deficit with a stunning volley from the edge of the box with four minutes left, but despite a late flurry they could not find an equaliser.
A victory would have all but secured West Ham’s passage into the knockout stages but now they find themselves with work to do, lying level with Freiburg at the top of the group with Olympiacos two points behind.