A much changed Development Squad slipped to a 1-0 friendly defeat against a resilient Luton Town side at Rush Green on Wednesday.
The only goal of the game came after 14 minutes as visiting captain Matt Robinson powered a left footed strike into the bottom corner from outside the box.
Despite an improved second half from the Hammers, in which they attacked with more purpose and invention, they could not find a way through and one goal was good enough for the away side.
The Hammers featured the returning Paul McCallum as a lone frontman with Taylor Miles and Jordan Spence also handed starts as they looked to give some players precious game time during the break in Barclays Under-21 Premier League fixtures.
The first half saw the visitors on top for long periods and they could have been ahead as early as the third minute when Mark Cullen nodded over from a couple of yards out after a super cross from Shaun Whalley.
The returning McCallum had a similar chance just a minute later when Sean Maguire's cross was drilled across the box and just evaded the front man.
Luton took a deserved lead after 14 minutes as captain Robinson struck a powerful effort which found the bottom corner, leaving Vit Nemrava with no chance.
There was little for either side to get excited about until three minutes before half-time when the Hammers had the ball in the net but McCallum was ruled offside when tapping home a Matthias Fanimo cross.
After the break the young Hammers displayed more attacking intent as they began to ask questions of a Luton backline which had looked relatively untroubled.
On the 55-minute mark McCallum was denied again, this time seeing his header saved at point blank range after Sebastian Lletget had headed the ball into the box.
The home side were much improved but were still struggling to create meaningful opportunities and could have slipped further behind with 20 minutes left as Whalley cut in from the right flank, beating two players and striking a left foot shot which thumped the crossbar.
Substitute Blair Turgott made a difference when he was introduced but could garner nothing from several half chances as Luton made sure their visit to Rush Green ended in a deserved victory.
West Ham United: Nemrava, Driver, Shaw, Miles, Wearen (Turgott), Spence, Fanimo, Whitehead (Lletget), McCallum, Tombides, Maguire
Subs not used: Guzman Rosique, Sadlier, Page