Palace's development side suffered late heartache as Andreas Cornelius' last minute winner snatched a 2-1 victory for Cardiff City to end Gary Issott's side's four game unbeaten run.
The £8 million summer signing popped up in the final minute to poke home at the near post to complete the comeback at the Cardiff City Stadium and send his side top of the Premier Development League 2 South table despite Sullay Kaikai giving Palace an early lead.
Issott named the likes of Jose Campana, Paddy McCarthy and Aaron Wilbraham in his side and that experience helped the Eagles as they netted the first goal of the game on six minutes. Continuing his red-hot streak, Kaikai netted his seventh goal in as many under-21 games when a Campana free-kick wasn't cleared and the winger somehow found space in the box to blast the ball past Joe Lewis.
The lead could have been doubled two minutes later when Lewis saved from Wilbraham at point-black range after a great cross by Kyle de Silva but soon after Cornelius highlighted his eye for goal with a curling effort that arced just past the post.
Ibra Sekajja came on for the injured Osman Sow midway through the first-half and nearly found the net when he was slipped through on goal but again Lewis did well to stop the chance, and Campana also went close with a free-kick as Palace enjoyed the better of the opening 45 minutes.
Having played so well they wouldn't have wanted the hear the half-time whistle, and indeed just seconds into the second half Cardiff pulled level again when Rhys Healey, who scored the winner in the reverse fixture earlier in the season, drilled home a shot on the turn.
Further chances fell for Kaikai and Wilbraham before Healey was inches away from doubling his tally as he aimed for the far corner, but a frantic final five minutes saw Lewis Price thwart Cornelius at close range before Lewis again produced heroics to pull off a double save from Reise Allassani and de Silva before leaping onto the ball after a goalmouth scramble.
When Cardiff skipper Adedeji Oshilaja headed over from a corner with two minutes to go the game looked destined for a draw, but Cornelius pounced a minute into injury time to convert Theo Walton's cross and edge his side in front.
Kaikai nearly provided more drama at the death when he almost equalised from the restart but a great block by Bradley Williams helped the Bluebirds cling on to their last-gasp victory.
Cardiff City: Lewis, Coulson, Owen, Williams, Yorwerth, Oshilaja, Wharton, Healey, Cornelius, O’Sullivan, Bowen. Subs Not Used: Nugent, Wilson, Bell, Hawkins, Griffiths.
Crystal Palace: Price, Gordon, Dymond, Boateng, McCarthy (Chambers, 71), Taylor, Kaikai, Campana, Sow (Sekajja, 19(Allassani, 75), Wilbraham, De Silva. Subs Not Used: Gregory, George.