There is no player in Super League with quite the talismanic qualities of Jason Smith. Hull's injury-plagued captain played his first game since April - apart from one cameo appearance in July - and a side which had won just once in its previous seven games instantly looked like play-off contenders once more.
In the most extraordinary opening of the season so far, Hull ran in four tries in the first 11 minutes and Saints, who had been nine matches unbeaten going into this one, were simply brushed aside.
It was not just a matter of Smith, because his presence also coaxed hugely improved performances out of any number of his team-mates, but he was a torment to Saints every time he had the ball.
Not only that, but Smith was often an important distraction when he did not.
"Certain players are irreplaceable," said the Hull coach, Shaun McRae. "The freedom other players had with him on the field was something we'd forgotten about."
Hull were full of enterprise and invention from the start, Paul Cooke kicking from the first scrum and Saints having to scramble to keep out Colin Best. The danger was not averted, because the ball went immediately to the other side of the field for Smith to send Chris Chester over.
Chester and Richie Barnett released Gareth Raynor, before Barnett romped away for two of his own, the second an interception from Jason Hooper.
Saints did not register a point until Hooper got the ball out of the tackle for Mick Higham, but Hull hit back with two more tries before half-time. Smith's 40-20 kick and pass to Cooke created a first and then Cooke's clever kick set up Best.
With Smith taking a rest on the bench, Saints started the second half with a try from winger Anthony Stewart, but back came the maestro to put one on a plate for substitute Peter Lupton with a sublime chip.
Keiron Cunningham got one try back, but then Smith, and a superb pass from Alex Wilkinson, gave Raynor his second try to round off Hull's best display of the season.
The Saints' coach, Ian Millward, refused to blame the Smith factor alone for the end of his side's long winning run. "We weren't good enough early on and we made some poor defensive decisions," he said.
Millward also added that he had been happy with the performance of centre Willie Talau, his new signing from Canterbury Bulldogs, on a difficult debut.
Hull: R Horne; Best, Yeaman, Barnett, Raynor; Cooke, J Smith; Greenhill, Last, King, Fletcher, Ryan, Chester. Substitutes used: Carvell, Dowes, Wilkinson, Lupton.
St Helens: Wellens; Stewart, Newlove, Hooper, Gardner; Long, Higham; Mason, Cunningham, Ward, Stankevitch, Bennett, D Smith. Substitutes used: Jonkers, Wilkin, Jones, Talau.
Referee: A Klein (London).
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