Hull City were left to rue Matty Fryatt's first-half penalty miss as they were beaten by Barnsley.
The 25-year-old striker saw his spot-kick saved by Luke Steele before the home side took a two-goal lead.
Craig Davies broke the deadlock with a close-range finish before Andy Gray capitalised on a mistake from Adriano Basso to double Barnsley's lead.
Aaron McLean saw an overhead kick hit the bar for the visitors before Fryatt lashed home from the edge of the area.
The defeat was Hull's first in the league since 20 August but things could have been so different for Nigel Pearson's side.
Robert Koren had already seen an effort deflected wide before the visitors were awarded the spot-kick, when Robbie Brady was hauled down in the box by Jimmy McNulty.
However, Fryatt's low effort to the right was superbly tipped on to the post and out to safety by Steele.
In the second half, the home side made Hull pay for the miss as Davies finished superbly from a Gray pass before the latter tapped in a second after Basso had spilled Daniel Drinkwater's shot at the striker's feet.
Fryatt pulled one back for Hull with a shot from the edge of the area and could also have rescued a point soon after, but Steele was on hand to claw the effort away.
Davies could also have added to his tally for the Tykes though after he rounded Hull's substitute goalkeeper Peter Gulacsi but his shot was cleared off the line.