Crystal Palace opened the scoring in the eighth minute when Andy Johnson scored his 12th goal of the season.
Mikele Leigertwood played a throughball into the penalty box and Claude Davis was dispossessed by Johnson who turned to hit a ten-yard shot into the bottom right-hand corner of the net.
Chris Sedgwick's right-wing cross was volleyed by Lewis Neal but the ball was saved by Palace keeper Gabor Kiraly who was wearing his notorious tracksuit bottoms.
Brian O'Neil equalised for Preston after 27 minutes with a glancing header which looped over the Palace keeper into the top left-hand corner of the net from Graham Alexander's free-kick.
Fitz Hall was booked for bringing down Patrick Agyemang as he was about to race clear.
Just before half-time Dave Hibbert, making his first start for Preston, had a header saved by Kiraly.
Early in the second half Sedgwick crossed for Hibbert to head just wide and Hibbert then had a right-foot shot pushed away for a corner by Kiraly.
Palace boss Iain Dowie brought on Aki Riihilahti, Jon Macken and Marco Reich for Wayne Andrews, Clinton Morrison and Dougie Freedman and it almost brought rewards when Johnson headed the ball into the back of the net with a glancing header from a free-kick but the effort was ruled out for offside.
Preston manager Billy Davies brought on Daniele Dichio for Neal and Chris Lucketti for O'Neil and the hosts almost won the tie late on when Hibbert missed a great chance from just two yards out when he headed the ball wide after a corner by Alexander and a flick-on by Davis.