Bob Peeters struck a late equaliser for Millwall to secure a point from a 1-1 draw with ten-man Palace.
The Eagles looked set to hold on for victory following teenager Ben Watson's fantastic free-kick despite Tommy Black's mindless sending-off.
But ten-man Palace could not withstand a late onslaught from Millwall and substitute Peeters headed in from close range to rescue Mark McGhee's side.
The visitors went into the game sitting proudly on top of the table, but were without seven key players including strike pair Neil Shipperley and Dougie Freedman.
And it seemed to affect them as they struggled to impose themselves against a Millwall side that dominated possession in the first half without creating any clear-cut chances.
In truth, it was a fairly dull encounter until the game sparked to life on the hour mark with Black's dismissal.
The midfielder stupidly kicked out at Millwall new boy Kevin Muscat and rightly earned his second yellow card.
However, six minutes later Palace took the lead as 18-year-old Watson curled a brilliant 25-yard free-kick round the wall and left keeper Tony Warner rooted to the spot.
Millwall finally injected some urgency into their game and bombarded the Palace goal, but it looked as if they would be thwarted as Neil Harris was twice denied from close range.
But in the third minute of injury time Peeters attacked a Paul Ifill cross and powered his header past Cedric Berthelin from six yards.
Palace boss Steve Kember moaned: "I don't know where the referee got so much injury time from. And I thought Tommy's challenge was innocuous and should not have been a booking.
"I'm getting greedy because I was disappointed not to win, but I probably would have settled for a point before the match." Millwall manager Mark McGhee admitted: "We left it late and that is becoming a bad habit.
"We spoke and spoke about putting some tempo into our play, but we only showed some urgency after Palace had scored.
"But the positive thing is that I still feel we have a hell of a lot of improving to do and yet we have still got nine points from our first four matches."