Henderson stressed the importance of keeping Fulham at bay during long stretches of pressure from the home side – particularly in the second-half when, with Palace two goals to the good, the hosts sought a route back into the Cup tie.
He said: “They \[the fans\] were the 12th man today. Obviously, they helped us get through the first 20 minutes – and if Fulham get something in the first 20 minutes, it's a different game. They were always there with us.
“It can happen in a flick of a switch. If you concede a goal, 2-1, it changes the whole complexion of the game.
“So the boys at the back were phenomenal. They're talking to each other, communication, just helping each other out. And we've seen off all the threats and it's been a great day.
“As I say, the boys were phenomenal and they're putting a right shift today. Obviously, we're all delighted and we're just excited for the next round.”
That next round will be at Wembley in a month’s time, for the FA Cup semi-finals.
“We will go there full of confidence and give it a good go,” Henderson declared. “And do you know what? Why can't we bring success to this football club?
“The fans deserve it and everyone else around the club deserves it. We’ve got a fantastic manager. We'll be set up and we'll go there to win.”