Sunderland undid the good of recent weeks in a 3-0 defeat that did not seriously flatter Swansea City on Saturday but put David Moyes' side under huge pressure in the run-up to Christmas.
Moyes believes the outcome of his side's visit to the Liberty Stadium turned on a "tight" penalty award, when the ball hit Jason Denayer's upper arm as he jumped, in an attempt to block a cross.
Level at the interval, Moyes' team looked capable of going on to win. But from the moment Gylfi Sigurdsson converted the penalty, it was always likelier that Swansea would increase their lead than that the Wearsiders would equalise.