West Ham United U18s lost for just the second time in eight FA Premier Academy League matches on Friday, going down to a 3-1 defeat at Crystal Palace.
Despite dominating much of the first half and creating numerous chances, Academy Director Tony Carr's side were undone by two second-half goals from the Eagles.
Second-year scholar Sergio Sanchez (pictured) scored West Ham's goal, but the Hammers missed out on the chance to take over top spot in Group A by falling to a disappointing defeat in south London.
"We lost 3-1, but the biggest disappointment for us was that we should have been four goals ahead at half-time," said Carr. "We dominated the first half to such an extent that it was literally a matter of how many goals we were going to score.
"We were right on top but then they broke away and somehow managed to score the opening goal of the game. Sergio equalised when the ball dropped to him from a corner so we went in level at 1-1 at half-time.
"After the break, we literally gave two goals away as the bad habits that we displayed earlier in the season came back to haunt us. Sergio and Paco Craig, our two centre-backs, lost their shape and their discipline and it let Crystal Palace back into the game.
"For their second goal, their player looked as if he was a mile offside, but Paco had lost concentration and was playing him on and he ran through to score. For their third, Blair Turgott had done so well to track his full-back into our penalty area, but then he tried to pass the ball across the face of his own goal and their player intercepted and shot into the net.
"We threw everything at them in the closing stages and had what I thought was a perfectly good goal from Paul McCallum ruled out. The ball looked as if it had crossed the line by miles and their goalkeeper literally clawed it out from the netting, but the referee deemed it had not gone in.
"We hit the post and missed a couple of other open goals and ended up losing a game 3-1 that we should have had sewn up by half-time."
West Ham's youth team are without a fixture next weekend and return to action at Ipswich Town on Saturday 5 March.
West Ham United U18s: Wootton, Modelski, Driver, Craig, Sanchez, Turgott, Wearen (Moncur), Vose (Lletget), Tombides, Hall, Purdy (McCallum)