Crusaders gained revenge for a thumping earlier this season by keeping Harlequins rooted to the bottom of the league.
Two tries in the final 10 minutes took the home side to an 11th league win of the campaign and into the top eight play-off places.
The Crusaders, back at The Gnoll for the second time this season, made one change from the side which thrashed Salford 60-16 on Sunday with Ryan O’Hara coming in for Adam Peek in the pack.
Quins also made changes from the side beaten 42-18 at home by Hull, Danny Orr coming in instead of Luke Gale while Louis McCarthy-Scarsbrook started instead of Chris Melling.
Crusaders head coach Brian Noble had warned his side to not take the basement side lightly, given that Quins scored 50 points against them in June at The Stoop.
But they did not heed the advice early on as wing Jamie O’Callaghan was fed a neat pass from centre Tony Clubb to score the first try on the right wing.
Home half-back Rhys Hanbury replied in kind on 18 minutes when he linked with centre Jason Chan to go over in the corner.
But when the next opportunity appeared, Quins took it as full-back Ben Jones-Bishop went on a mazy run towards the right wing to find space and dash all 50 yards from the halfway line to score under the posts and give Orr a simple
It gave Quins a 10-4 half-time lead and the only glimmer of action for the next 30 minutes saw Clubb come within inches of the line and, at the other end, wing Luke Dyer chase a high cross-field kick.
It really was that poor and, although the ball may have been slightly slippery, it was by no means a bar of soap.
The game needed some spark to wake the fans up and, when Orr booted a penalty to take Quins 12-4 ahead, suddenly it brought the Crusaders to life.
They marched down the other end of the field and when Tony Martin made great ground on the right wing the ball was taken across the line for Chan to go through a gap and score.
Full-back Clinton Schifcofske landed the conversion to put the Crusaders two points down, and, within minutes, they were ahead as Hanbury grabbed his second with a run from 10 yards that Schifcofske converted.
And with no time left to mount a counter-attack, Quins left the field kicking themselves at losing a match they should have won.
Noble praised the resolve of his players as they climbed to an unaccustomed eighth place.
“We have won four on the bounce now and that kind of habit is good,” said Noble. “I don’t think I can cope with the amount of stress we placed on ourselves tonight but I’m absolutely thrilled for the players.
“It is a measure of how hard they have worked and it is a success story when you look at where we started in January.
“It was a slow ruck and a little bit of drizzle made it an unattractive game at times. Both teams were trying to play football but both defences squeezed in the ruck area which made it slow.
“And I thought we were a bit flat but, with 10 minutes to go, a couple of fabulous plays from people brought us over the line.
“We had to wait until the end to give us what we wanted.”
Quins head coach Brian McDermott, meanwhile, was left deflated by his side’s late
“They found themselves with two tries at the end which put it to bed. There was an interception for one try and it was an unfortunate bounce and slip for the second,” said McDermott.
“There will not be too much I will be saying in review of what the fellas should have done differently.
“It was a greasy game and there was pretty tight defence. There was some solid hits and the game was played in the middle for large parts.
“I don’t think we dominated Crusaders and they didn’t dominate us. It was that type of game.”
And there was better news for Crusaders fans after the match, with Noble revealing that Welshman Gareth Thomas, who has been out with a groin problem for three weeks, should be fit to return for their final three matches against Hull, St Helens and Hull KR.
See full story in the Leader