Willie Talau scored one of St Helens' five tries
St Helens (4) 25
Tries: Gilmour (2), Talau, Gardner, Roby
Goals: Wellens (2)
Warrington (12) 14
Defending champions St Helens reached the semi-finals of the Carnegie Challenge Cup with a hard-fought win over Warrington at Knowsley Road.
Tries: Penny, Fa'afili
Goals: Briers (3)
Saints went ahead after a minute with a try from Lee Gilmour but Warrington hit back through Kevin Penny and Henry Fa'afili to lead 12-4 at half-time.
Tries from Willie Talau and Ade Gardner levelled the score at 12-12.
But Saints went back in front when Gilmour pounced for a second and James Roby's late try sealed the tie.
St Helens have now reached the last four of the Challenge Cup seven years in a row, while Warrington, who have lost seven of their last eight games, have not won at Knowsley Road for more than 13 years.
There wasn't a huge amount of class or skill but we hung in there longer than our opposition did
Saints coach Daniel Anderson
Saints came out of the blocks at a rate of knots as Gilmour scored from a chip-through from Talau.
Warrington were simultaneously floored by the loss of star forward Adrian Morley, who suffered a blow to the head and was off the pitch for more than an hour.
But the Wolves rallied and went close twice, both times squandering golden scoring opportunities.
First, Fa'afili wasted a two-on-one overlap with a mistimed pass to his winger, before Ben Westwood dropped a ball with a gaping view of the try-line in front of him.
Saints upped their intensity around the 20-minute mark but Warrington defended staunchly before hitting back with Penny's stunning solo effort.
We came here to win the game and we're gutted that we're going home without it
Penny took the ball tight on the left touchline and his impressive pace took him past the despairing tackles of Matt Gidley, Gardner and Paul Wellens.
Lee Briers converted and four minutes late Warrington stretched further clear when Fa'afili dummied his way over from close range.
St Helens immediately cut the deficit after the break when Francis Meli caught Long's cross-kick into the corner and offloaded to the supporting Talau to score.
Saints built on their momentum and soon put Gardner over in the right corner after a flowing move upfield.
Wellens missed Saints' third conversion, which looked costly when Briers added a penalty on 52 minutes.
But the home side roared back into the lead when a good break from Jon Wilkin, and support from Sean Long, sent Gilmour under the posts.
Wellens opened the gap with a penalty and Long edged the lead to seven points with a late drop inside the last 10 minutes before Roby scampered over to remove any doubt.
St Helens coach Daniel Anderson:
"Credit to Warrington. They lost a pretty inspirational player in the first tackle of the match and forced us into a zone that we haven't been in. They flustered us and forced some errors.
"I thought we won the game on determination. There wasn't a huge amount of class or skill but we hung in there longer than our opposition did and got points.
"I thought it was a brilliant defensive performance in the second half. We were extremely motivated and aggressive.
"Our attacking play was poor by our standards but that was a bit to do with our opposition and the weather. It was stinking hot out there."
Warrington coach Paul Cullen on losing Morley:
"It certainly tested our character and I thought the way the players responded was absolutely magnificent. To suffer that and go in front at half-time was certainly remarkable.
"The guys refused to give in. I thought defensively it was a massive effort. We were a couple of players short of achieving our goal.
"We came here to win the game - that was very evident about the way we went about our business - and we're gutted that we're going home without it."
St Helens: Wellens, Gardner, Gidley, Talau, Meli, Pryce, Long, Fozzard, Cunningham, Cayless, Gilmour, Wilkin, Clough.
Replacements: Roby, Graham, Hargreaves, Fa'asavalu.
Warrington: Grose, Penny, Johnson, Fa'afili, Riley, Clarke, Briers, Wood, M. Gleeson, Morley, Westwood, Parker, Wainwright.
Replacements: Sullivan, Bracek, Rauhihi, Pickersgill.
Referee: R Silverwood (Dewsbury)