Hull FC (12) 18
Tries: Lyne Goals: Tickle 7
Crusaders (8) 16
Tries: Dyer, Lupton Goals: Schifcofske 4
Forward Danny Tickle joined Hull FC from Wakefield in October 2006
Crusaders' play-off hopes were dealt a cruel last-gasp blow which had coach Brian Noble fuming at the KC Stadium as Danny Tickle kicked Hull to victory.
Noble's men looked to have secured a draw when ex-Hull man Peter Lupton ran in a try four minutes from time.
But 12-man Hull, who had seen Jordan Tansey sent off for a spear tackle late on, bounced straight back.
And Tickle's seventh kick of the night in the dying seconds ensured that Hull will stay above Leeds in fourth.
Crusaders will remain in the last of the play-off spots this weekend thanks to rivals Castleford's crushing home defeat by Leeds.
But the dramatic and controversial end could earn Noble a Rugby Football League reprimand.
The Crusaders coach confronted referee James Child on the touchline and then on the field at the end after the official awarded a penalty for the foul on Reece Lyne that allowed Tickle to win it for Hull from the touchline.
The former Bradford, Wigan and Great Britain coach had to be restrained by the fourth official as he looked to go on the field during the game and vent his anger, and he was visibly fuming as he eventually stormed down the tunnel.
Hull knew that they had to win to remain ahead of fifth-placed Leeds, who were crushing another play-off chasing side Castleford 38-6 at The Jungle.
But they made hard work of it in a game hampered by a torrential downpour just before kick-off.
The early action on the field was no better for the home side, centre Jordan Turner leaving the field with an arm injury after just five minutes.
With no backs on their bench they were forced to employ prop Epalahame Lauaki as an emergency centre and nearly went ahead when Tom Briscoe almost got on the end of Tansey's kick.
As it was, Crusaders drew first blood when, after Jarrod Sammut's pinpoint kick to the corner caught Lyne napping, winger Dyer went over on the quarter hour for his first try since 25 April.
After landing the conversion, Clinton Schifcofske then added a penalty seven minutes later for an 8-0 lead.
But, on 25 minutes, Lyne atoned when he raced on to Kirk Yeaman's offload to grab his second try of the season.
Danny Tickle added three more kicks in the final 10 minutes before the break for a 12-8 half-time lead.
Schifcofske's boot narrowed the gap at the start of the second half, only for two more kicks by Tickle to stretch Hull clear at 16-10.
But there was a to be a couple of huge final twists in the tail.
Full-back Schifcofske broke through for the visitors, but appeared to be spear tackled by Tansey.
And, after the Hull man was dismissed, Lupton took advantage of the extra man to burst onto Sammut's pass, Schifcofske converting to level at 16-16.
But there was still time for Lyne to be blocked off as he chased a kick, and Noble lost his rag before Tickle converted.
Hull FC coach Richard Agar said:
"I didn't see the incident but, over the 80 minutes, I've certainly got some empathy. I think everybody felt that. It was a difficult night with the conditions. The penalties dictated the way the game was played.
"As form the sending off, he was very quick with his card.
"He didn't take much time so he must have been confident with his decision. I am a person that believes tipping, be it accidental or not, is something we don't need to be seeing.
"We would expect him to catch something for that, but you never know."
Crusaders coach Brian Noble said:
"I confess to being absolutely seething. I'm as cross as a cross man in a cross shop. That's putting a light-hearted slant on it, but it's the hopes and aspirations
"We deserved more than we got and I hope I get some decent answers but I'm not sure I will.
"The touch judge gave the penalty at the end. I don't know where he's from but I hope it's not anywhere near Castleford.
"I don't sleep after games and I might not sleep for two after this. I feel so sorry for the players.
"You can get all the apologies you want but it doesn't change it. We could have been sitting pretty with three points on Castleford.
"We weren't great and I've told the players that, but they didn't deserve that. "We deserved at least a point and to come away with nothing is a bitter pill to swallow."
Hull: Tansey, Lyne, Turner, Yeaman, T Briscoe, Washbrook, Berrigan, O'Meley, Houghton, Radford, Manu, Tickle, Fitzgibbon.
Replacements: Dowes, Cusack, Lauaki, Moa.
Crusaders RL: Schifcofske, Dyer, Martin, Chan, Youngquest, Sammut, Hanbury, O'Hara, Withers, Bryant, Winternstein, Hauraki, Lupton.
Replacements: Lee, James, Peek, Trimarchi.
Referee: J Childs (RFL).