Crystal Palace lost their 13 game unbeaten home record to fellow strugglers Scunthorpe 2-1 at Selhurst Park, allowing the Irons to close the gap on the fourth-bottom Eagles to just three points. Dougie Freedman's side, who would have been nine points clear of the drop zone with a victory, now face a tense end to the season.
"It was a really bad day at the office," said Freedman.
"We've been on a great run at home but it's come to an end just when we didn't want it to.
"We were maybe a bit tense and Scunthorpe were two or three yards sharper than our players. I've no complaints about losing the match.
"But we will take our medicine and move on. What I have to ask now is how will we respond?"
Freedman's misery was compounded by an injury to on-loan Everton striker James Vaughan, who needs a scan on his ankle and could miss the run-in.
Iron boss Alan Knill's side now have a fighting chance of survival.
"It's a massive win," he admitted.
"It was billed as a must-win game and it really was.
"If they had gone nine points in front it would have been difficult with four games left. We've cut it to three and it gives us a belief that we can still do it.
"We are always on at the them that they are better than they have shown.
"From start to finish it was a really good performance by the team."
Scunthorpe's Joe Garner was sent-off for receiving two bookings and Scannell saw red for lunging at Andy Hughes.