Crystal Palace boss Dougie Freedman admitted Dean Moxey's red card was costly as Millwall came from two goals down to snatch a 2-2 draw in the south London derby.
In-form Palace were 2-0 up and apparently cruising as half-time approached thanks to a stunning goal from skipper Mile Jedinak and Damien Delaney's header. But after Moxey saw red for handling Darius Henderson's header on the line just before the break, Liam Trotter tucked in the penalty to drag Millwall back into the game.
Palace survived with 10 men until the 77th minute, when Mark Beevers reacted quickest from a corner to snatch a point.
"Only Dean can tell you what he was thinking at the time, but it looked instinctive," said Freedman.
"I'm sure if he had his time over again he'd let the ball go into the net and we could have gone on to win the game with 11 men.
"Unfortunately he didn't get too much sympathy at half-time, we had to regroup and be mentally strong as we were a man down."
Jedinak opened the scoring in spectacular fashion in the 35th minute, picking the ball up 35 yards out and crashing a fierce, swerving drive past David Forde. Four minutes later Palace doubled their advantage, Owen Garvan swinging in a free-kick and Delaney rising highest to glance a header into the net.
But after Moxey handed Millwall a lifeline - literally - the 10 men were finally pegged back when Josh Wright swung in a corner and Beevers diverted the ball in with his thigh.
"I was very pleased with my players coming back from two down away from home," said Lions manager Kenny Jackett.
"The second half was a dominant performance. We persevered against a resilient Palace side and got back into the game."