Tottenham blew the chance to open up a seven-point gap to fifth-placed Newcastle and compounded the misery of their midweek FA Cup defeat to Sheffield United by losing 1-0 at Wolves.
This was the game, after all, for which Harry Kane, Cristian Romero, Dejan Kulusevski and Oliver Skipp were rested at Bramall Lane but that gamble by Antonio Conte and Cristian Stellini has now doubly backfired after Adama Traore's 82nd-minute winner.
The quartet returned to the XI at Molineux but could not help Spurs to a win which would have put clear daylight between them and the Magpies, who lost 2-0 at Manchester City in the early kick-off.
The result will make the decision to play a weakened team in the fifth-round tie all the more infuriating for supporters and only adds to the pressure of Wednesday's Champions League last-16 decider against AC Milan - with Conte's side trailing 1-0 from the first leg at the San Siro.
Spurs' hopes of keeping supporters engaged for the run-in may rest on that tie but their ability to manage big games and pressure points in the season was again exposed by Julen Lopetegui's side.
Stellini - whose spell in charge looked set to revitalise Spurs' season but has now ended with two dispiriting 1-0 defeats - can point to bad luck in the Black Country as Spurs twice hit the woodwork and peppered Jose Sa's goal with efforts before Adama finished smartly off the underside off the crossbar.
Pedro Porro's free-kick smacked the bar in the first half, which also included Sa saves from Heung-min Son and Dejan Kulusevski, while the South Korean also struck the horizontal just after the restart, in what felt like a pivotal moment in the game.
Stellini and the absent Conte were not blameless for the result, however.
If their team selection was a problem midweek, here it was their substitutions that were off. Needing a goal as the clocked ran down, Stellini sent on Lucas Moura first, leaving Richarlison and January signing Arnaut Danjuma on the bench.
Defender Emerson Royal was next to be introduced, and Richarlison, a £60million summer signing, was given just five minutes once Spurs were already trailing.
By contrast, Lopetegui had used all five of his substitutes by the midway point of the second half (at least one change was, admittedly, enforced) and the tweaks enabled the hosts to get back in the game after Spurs controlled the first 55 minutes.
Stellini and Conte, presumably watching again from Italy and communicating with the bench before his return to the country on Saturday night, just failed to react.
It said a lot that Fraser Forster was probably Spurs' standout player in the end, making sharp saves from Raul Jimenez and Ruben Neves (twice), and parrying the Mexican's shot before Adama pounced.
Spurs now must lift themselves for Milan and hope to avoid another result which would leave the club fighting on a single front and supporters increasingly apathetic.
