St Helens moved into second place in Superleague for the first time this season but at a heavy price.
Keiron Cunningham's distinguished career could be over if he has suffered the broken jaw that is feared. "That would be tragic," said his coach, Mick Potter. He added that there had been a suspicion of a raised arm in the tackle that did the damage to the 33-year-old hooker, who is to retire at the end of the season.
Saints also face losing the services of Kyle Eastmond with a hip injury and Matty Ashurst with knee damage on a night when, as Potter said, most of the shine was taken off their victory.
Crusaders have a habit of starting matches slowly, but not this one. Within the first two minutes, they had capitalised on Bryn Hargreaves' fumble in the tackle, keeping the ball alive cleverly for their leading try-scorer, Vince Mellars, to show his worth by forcing his way over.
That was the cue for Eastmond to show his value to St Helens. First he latched on to a pass, admittedly a suspiciously forward-looking one, from Chris Flannery for the equalising try. Then his kick created a try for Paul Wellens, scored at the cost of a shuddering collision that left the goal-posts vibrating like a tuning fork. The home side tied up the scores again thanks to exceptional work from one of their small colony of English players, Peter Lupton drawing in two tacklers to give Frank Winterstein a clear run in.
Luke Dyer was denied what would have been a spectacular third Crusaders' try by an offside ruling and that looked a particularly pivotal moment when Saints went straight to the other end and scored, Jon Wilkin lobbing his pass into the waiting arms of the unmarked Ade Gardner. It was enough to give them the half-time advantage in what had otherwise been a finely balance first 40 minutes.
Rocky Trimarchi was brought back for a forward pass and Rhys Hanbury almost intercepted from Eastmond as Crusaders tried to wrest back the initiative after the break.
A bigger worry for Saints and potentially for England was the sight of Eastmond limping off. Hargreaves almost got over for Saints, but Crusaders then looked dangerous on the counterattack and Gardner had to make a saving tackle on Nick Youngquest. Saints consolidated their lead, however, when Matt Gidley showed the craft they will be losing next season with an overhead pass to put Jamie Foster in.
Jonny Lomax just managed to deny Mellars a second from a kick as the home side showed no sign of conceding defeat. James Roby's clinching try looked short of the line to every Welshman in the crowd, but it counted.
Crusaders: Schifkofske; Dyer, Martin, Mellars, Youngquest; Lupton, Hanbury; O'Hara, Withers, Bryant, Winterstein, Chan, Hauraki. Substitutes used: Lee, James, Thackray, Timarchi.
St Helens: Wellens; Foster, Gidley, Meli, Gardner; Lomax, Eastmond; Graham, Roby, Hargreaves, Flannery, Wilkin, Moore.
Substitutes used: Cunningham, Puletua, Ashurst, Emmitt.
Referee: R Silverwood (Mirfield).