6,000 loud and proud Eagles took over the famous Clock End, creating an incredible spectacle at the Emirates Stadium.
Goalscorer Eddie Nketiah later said the backing from that end of the ground pushed the Palace players on in the closing stages, when a remarkable comeback looked a real possibility.
Arsenal had gone 3-1 up with only nine minutes remaining. But, with the away end still making constant noise throughout, Palace refused to let the tie fizzle out, Nketiah's smart header setting up an exciting finish.
Manager Oliver Glasner also paid tribute to the superb backing in his post-match interview.
"Also thanks to our fans [for their] great support today," he said. "It was great. They pushed us, especially at the end. We could feel like maybe something was possible.
"But we didn't get this 3-3 [goal]. It would have been amazing shooting the penalties, hopefully in front of our fans."
Check out some great shots of the away end in our below gallery.
