West Ham United ended their Europa League group stage campaign with a 1-0 loss to Dinamo Zagreb at home.
The Hammers had already won Group H, securing their place in the tournament's last 16 in March.
Thus, David Moyes named a starting XI including five players aged 20 or under.
An inexperienced defence conceded after only three minutes when Mislav Orsic curled the ball into the top corner.
17-year-old Sonny Perkins came close to scoring but headed over Harrison Ashby's cross.
It is a huge result for Dinamo, who now finish second in the group and advance to the knockout round play-off.
West Ham will now switch their focus to Sunday's clash with Burnley at Turf Moor.