Leeds United's pursuit of a runners-up place has finally faltered - with a defeat over which they can have no excuses.
Jobi McAnuff's 43rd-minute winner came from one of no fewer than four clear openings Crystal Palace manufactured before the interval in underlining their own promotion hopes.
Leeds could find no such cutting edge, although their manager Kevin Blackwell promised: "There are more twists ahead, believe me. We had plenty of pressure and just didn't create enough.''
This long-awaited game in hand was seen as the one for Leeds seriously to turn up the heat on Sheffield United. Instead, the result was excellent news for the Blades and the club who leapt into third spot on Monday, Watford. Palace's best hope remains the play-offs - a route that holds no fears for them following their graduation two years ago.
"We were superb in the first half and resolute in the second,'' said their manager, Iain Dowie. "We should have been further ahead but Andy Johnson showed he isn't just a goal-getter. He's a provider as well.''
Palace should have led inside four minutes. Of all people, Johnson passed up a wonderful opportunity created by a McAnuff cross and a dummy by Clinton Morrison. Johnson had time to compose himself but his shot was blocked by the legs of the diving Neil Sullivan.
Following a Jonathan Douglas header that bounced wide, Johnson erred again, this time dragging wide with his left foot after his familiar pace had taken him clear at an angle on to McAnuff's pass.
The game continued to carry a strong whiff of goals. Gary Kelly produced a fierce 25-yarder that Gabor Kiraly watched through a cluster of players before magnificently fingertipping away at full stretch.
Palace's wastefulness was most marked on the half-hour. Sullivan palmed out Mikele Leigertwood's well-struck effort and was still regaining his feet when Fitz Hall sidefooted the rebound wide from three yards. Only the fact the chance fell to a centre-half could account for it being squandered.
The lead was long overdue when the influential Michael Hughes fed Johnson, who bore down on the centre of Leeds' defence before slipping a pass for McAnuff to drive hard and low across Sullivan.
Leeds' 10-match unbeaten run should already have been in ruins and they had to be patient to muster any threat in a much tighter second half. Matthew Kilgallon was left unmarked at an Eddie Lewis free-kick, only to see his bouncing header pushed out by Kiraly and, in the same attacking flurry, Liam Miller brought a near-post save from the keeper.
Substitute Robbie Blake drove wide before Leeds threw Jermaine Beckford, recently signed from Wealdstone, into a gung-ho but unavailing late assault.
Leeds United (4-4-2): Sullivan; Kelly, Butler, Kilgallon, Crainey (Beckwith, 76); Miller, Douglas (Bakke, 85), Derry, Lewis; Healy (Blake, 62), Hulse. Substitutes not used: Bennett (gk), Moore.
Crystal Palace (4-4-2): Kiraly; Boyce, Ward, Hall, Leigertwood; Riihilahti, Watson, Hughes, McAnuff (Reich, 90); Johnson, Morrison (Soares, 74). Substitutes not used: Speroni (gk), Popovic, Freedman.
Referee: P Joslin (Nottinghamshire).Reuse content