Palace climbed out of the bottom three thanks to a 1-0 win over Middlesbrough, a result that keeps Boro in the relegation mix. James Vaughan, on loan from Everton, slammed home his seventh goal of the season to decide the match.
Sheffield United drop into the relegation zone after a 3-0 loss at Ipswich Town.
Damien Delaney headed home a 29th-minute free-kick from Jimmy Bullard then set up David Norris to double the lead.
The Tractor Boys could even afford a missed penalty from Grant Leadbitter before Connor Wickham grabbed a late third.
The Blades' misery was compounded when Rob Kozluk and Lee Williamson were dismissed.
The only team worse off than the Iron are Preston North End, who are 10 points from safety after a 4-0 drubbing at home to Bristol City.
Andy Keogh, the former Iron striker, put the Robins ahead after just five minutes. A second-half brace from David Clarkson followed by a Brett Pitman goal put the result beyond doubt.
Nottingham Forest's 1-0 win over Watford at the City Ground - secured thanks to a goal from Marcus Tudgay - saw them move up to second.
They replaced Norwich City, who were beaten 2-1 at Burnley. Dean Marney put the Clarets ahead before Grant Holt levelled, with Jay Rodriguez netting the winner after 81 minutes.
A late goal from David Nugent secured Portsmouth a 1-1 draw at home to Derby County, after Steve Davies had put the Rams ahead.
Leeds United defeated Coventry City 1-0, with Millwall also securing a single-goal success over Doncaster Rovers.
Leicester City beat Barnsley 4-1 to maintain their steady climb up the table.