St Helens were pushed all the way by the second-placed team
St Helens: (6) 12
Tries: Gardner, Meli
Goals: Lyon 2
Hull: (6) 8
Goals: Cooke 2
St Helens booked their place in the Grand Final at the first time of asking with a narrow win over Hull in a pulsating qualifying semi-final.
Ade Gardner strolled through some statuesque defending from Hull to give St Helens the lead on 18 minutes.
Hull hit back through Kirk Yeaman soon after to bring the scores level.
With the tension mounting both sides kicked penalties to take the score to 8-8, but Francis Meli's 61st-minute try proved to be just enough for Saints.
St Helens were restricted to one-out rugby in the early stages as Hull's intensity in defence laid down a marker and helped them dominate territory.
But the league leaders slowly started to assert themselves, with line breaks from Jason Cayless and Jon Wilkin serving notice of their intentions.
The home team's opening try, though, was a gift, coming after Hull's defence switched off.
A looping pass from Paul Wellens missed its intended target, eventually falling, via Jamie Lyon's outstretched boot, to Gardner, who picked the ball up and ambled over the line.
Hull refused to let St Helens' array of attacking talent get on the sort of roll which has destroyed a series of Super League teams this season.
And they swiftly hit back through Yeaman when Meli was controversially adjudged to have knocked on.
The ball flowed through the hands of Richard Swain, Paul Cooke and Richard Horne before Yeaman powered through Sean Long's tackle on the line.
Hull were unlucky not to repeat their June victory over Saints
With the scores level at 6-6, Long looked to suffer from an attack of the nerves as he sent his subsequent kick-off out on the full to hand the initiative straight back to Hull.
Saints made a total of 10 first-half errors, with a desire to overcomplicate things near the Hull line costing them several opportunities.
Hull came out all guns blazing for the second half, and the decision to go for goal on 44 minutes through Cooke spoke volumes about how little there was to choose between the sides.
Lyon followed suit five minutes later to bring the scores level at 8-8.
Saints, with a vociferous home crowd behind them, started to turn the screw and took the lead again when Meli plucked the balloff his laces before diving over after great work by Long and Lee Gilmour.
Hull refused to give up, but the errors which had characterised St Helens' first-half play began to creep into the visitors' game as they became increasingly desperate.
Keiron Cunningham was held up over the line by yet more brave Hull defence in a breathless final quarter, while Willie Talau had a late try ruled out after Leon Pryce's pass was ruled forward.
Hull, who finished second in the Super League table, have a second chance to reach their first ever Grand Final.
On 6 Octoer, they will take on the winner of Saturday's match between defending champions Bradford and Warrington for a place in the 14 October showpiece.
St Helens coach Daniel Anderson:
"It was very exciting and the nerves are still jumping.
"I was very impressed by both teams and there was some absolutely fantastic defence on display. It was a wonderful exhibition of semi-final football.
"Defence has been the cornerstone of everything we've done this season and it's what won us this match."
Hull coach Peter Sharp:
"It was a tremendous effort, but we came up a little bit short.
"It was a tough match, very hard and very skilful and we will take something from it. We'll regroup and be ready for next week.
"I thought we didn't get the rub of the green all night. There were some
dubious decisions to say the least."
St Helens: Wellens, Gardner, Lyon, Talau, Meli, Pryce, Long, P. Anderson, Cunningham, Cayless, Gilmour, Wilkin, Hooper.
Replacements: Roby, Graham, Bennett, Fa'asavalu.
Hull: Tony, Briscoe, Yeaman, Domic, Raynor, Cooke, R. Horne, Dowes, Swain, Carvell, Radford, McMenemy, Washbrook.
Replacements: King, G. Horne, Wheeldon, Whiting.
Referee: A Klein.