Alan Pardew's side have conceded 11 goals in their last five games
Crystal Palace's 3-0 shut-out of Southampton at the start of the month was supposed to signal a turning point for Alan Pardew's men.
The week previous, the Eagles had come undone thanks to two late Swansea goals and lost 5-4 away to the Welsh club. Palace had - on the face of things - corrected some of the errors they were making defending set-plays and were able to capitalise upon Christian Benteke's wonderfully finishing ability.
However, after Saturday's 3-3 draw away to Hull City, the same issues appeared to be raising their heads.
"The defenders aren't playing like the defenders of who have been here for two or three years," Pardew said today ahead of the visit of Manchester United to Selhurst Park.
"It's not like there's anybody new in there. They've done a brilliant job in the past. Sometimes [with performances] it's a little bit of luck and a little bit of confidence as well.
"But I've got full resolve and full commitment to those guys and the goalie. Of course, defending is a team duty and never more so than now in the Premier League.
"Everybody has a responsibility to defend, including substitutes. That's the area we're still looking to improve on. Sometimes subs will come on and not sured us up as well as they should have."
Christian Benteke (left) and Wilfried Zaha have been two of Palace's stand-out performers, but problems at the back continue to undo their good work up front. Image: Anna Gowthorpe PA Wire/PA Images
Scoring goals hasn't been as much as of an issue as defending, as Pardew pointed out: "10 goals in three games we've scored. We obviously need to tighten up and I think Southampton was the benchmark for us in terms of a defensive display and we need to reproduce that against a United team who have found a bit of form."
Palace face United, league leaders Chelsea and Arsenal over the course of their next four games and Pardew was quick to acknowledge that with games as potentially tricky as these, the time is now to plug up their backline.
"We're not critics who moan about this or that, we have to find solutions and that's the hard part of this game. It's easy to say something is wrong or someone is wrong, but you've got to find solutions.
"We were pleased with the way we defended set-plays over the weekend because it was a problem two games previous. So we've ticked one little box, now we have to get back to how we performed against Southampton."