The Eagles' under-21 side's mixed fortunes continued at Brentford as they fell to a three goal defeat, despite remaining on level terms until seven minutes from time.
Bees trialist Keshi Anderson rattled in a six minute hat-trick to hand the home side a moral-boosting victory and condemn Palace to a second defeat in succession, leaving them with four wins and four defeats from their previous eight games.
Brentford enjoyed the brighter start but Aaron Greene and Charlie Adams failed to hit the target before ex-Palace youngster Jermaine Udumaga finally tested David Gregory with a tame effort.
However the keeper was caught out when Sam Saunders attempted an audacious 50 yard free-kick which sailed over Gregory's head and into the net, however the wondergoal was ruled out as the ball wasn't dead when it was struck.
After that let-off Palace began to grow into the game and Ryan Inniss went close with a header and Morgan Ferrier scuffed a shot wide before being thwarted with a second attempt by Bees stopper Richard Lee as Gary Issott's side began to find a foothold in the contest.
Just before the interval the in-form Kyle de Siva then forced Lee into another save, and Udumaga should have done better when he shot wide as an entertaining half drew to a close.
After the restart the chances continued to come thick and fast and Josh Laurent picked out Adams who could only steer the ball wide from a good position, before the visitors came close to finding the opening goal when Reise Allassani found some space in the box to take aim but saw his shot come back off the post.
That proved costly as on 83 minutes the Bees stung Palace to take the lead in fortuitous fashion. Nico Yennaris tucked the ball into substitute Anderson who saw his shot flick off Inniss, strike the crossbar and end up in the net to grab the lead.
Palace piled forward in their attempt to try and restore parity but that meant they were vulnerable at the back and after a counter-attack, Anderson volleyed in a second when Gregory parried an Udumaga strike.
Then just a minute from time the striker completed his treble when he headed in a Josh Clarke cross to hand his side a highly unlikely 3-0 victory.
Brentford: Lee, Clarke, O’Shaughnessy, Craig (Clayton 60), Greene, Calvet, Yennaris (Ferry 84), Adams, Laurent, Saunders (Anderson 66), Udumaga. Subs not used: Milenge, Marsh-Brown.
Palace: Gregory, Egbo, McCarthy, Inniss, Berkeley-Agyepong, Black (Adarabioyo 85), Boateng, Dymond, de Silva, Allassani, Ferrier. Subs not used: Simpson, Magri, Sow, Akiotu.