Sunderland manager David Moyes criticised referee Craig Pawson's decision to give Swansea City a penalty as his side slumped to the bottom of the Premier League with a 3-0 defeat at the Liberty Stadium.
The Wearsiders had won three of their previous four encounters, but shipped three second-half goals in Wales as Swansea eased to victory to move out of the relegation zone.
Swansea's first goal came as Gylfi Sigurdsson converted from the spot after Jason Denayer was harshly adjudged to have handled Wayne Routledge's cross in the area.
Moyes' men never recovered from that setback and Fernando Llorente added a brace to wrap up the points for Swansea, leaving the Scot to lament what he viewed as the turning point in the contest.
"It did turn the game," Moyes said of the penalty.
"My view of it was that he [Denayer] goes to block it, he's not looking at the ball, he's got no intention, he's two yards away from the ball, very difficult, so I think it's the wrong decision."
Sunderland now face a busy Christmas period that features games with Chelsea, Manchester United and Liverpool and Moyes wants his charges to put Saturday's result behind them.
"We've been on a good run, we didn't play as well as we have done," he added.
"That's the way the league is, we won the other week against Hull 3-0 at home, Swansea have beaten us 3-0, it's going to be tight round that end of the league.
"We're improving, six weeks ago you would have said we were written off. We're back in it, what matters is where we are come May, but we're certainly back in with a fighting chance."