Sean Long scored a try and kicked four goals for St Helens

Holders St Helens reached the last four of the Challenge Cup but they were made to work hard before shaking off a determined Hull KR outfit.

Second-half tries by Sean Long and Ade Gardner helped give them an eighth successive semi-final appearance.

After going behind to an early Paul Cooke try, Saints roared back through Willie Talau and Maurie Fa'asavalu before Daniel Fitzhenry responded.

Long's score was cancelled out by Jake Webster but Gardner's try clinched it.

The home side made a blistering start with Cooke landing a 40-20 kick inside the opening minue and from the resulting possession he raced onto Michael Dobson's grubber kick to touch down.

But Saints hit back with two tries in the space of five minutes. First Long reversed the direction of play and Lee Gilmour sent Willie Talau over before Fa'asavalu barged through for a second.

606: DEBATE Can't knock the Saints, but they had the benefit of two big refereeing decisions gloriousrufusrocky

Hull KR tried to get back into the game but were twice denied by referee Ashley Klein.

Shaun Briscoe and Ben Cockayne both thought they had scored but Klein spotted an obstruction in the build-up to the first effort and was unhappy with the grounding of the second.

But they did pull level when Fitzhenry raced 80 metres to the line and he almost added a second early in the second half but failed to hold onto the ball.

Saints edged back ahead as Long's tricky run carried him to the line but Rovers were not behind for long, however, as Paul Wellens missed Dobson's kick and Webster pounced, with Cooke again adding the extras to level.

Fa'asavalu was placed on report for a high tackle on Briscoe but Cooke was wide with the resulting penalty.

Saints claimed the decisive try in the 70th minute after good work by Talau and Long sent the ball out to Gardner to score in the corner.

The game was still not over as Chris Chester lost the ball over the line looking to bring Rovers back level yet again but Saints held on.

Hull KR coach Justin Morgan

"I don't think we were robbed, we did enough to deserve to win. I couldn't see whether Briscoe's effort was a try or not. I can't tell after one look. I will live with the decisions but it was a good advert for video referees at all games.

"This is a massive clash. If a video referee shows it not to be a try then, fair enough, I will have to accept the decision, but my natural instinct was that it was a try.

"I could have asked for a bit more patience and composure. We had chances but weren't capable of executing them."

St Helens coach Daniel Anderson

"The 17 men had to do a job. Hull KR were exceptional in their desire. If it was a league game maybe we wouldn't get there for some of those tackles.

"I don't know what it is, we just had to do it because there is no redemption. We just wouldn't give it up.

"They were a little unlucky but I don't think we were unlucky."

Hull KR: Briscoe, Fox, Cockayne, J. Webster, Fitzhenry, Cooke, Dobson, Vella, Fisher, Crossman, Newton, Gene, Walker.
Replacements: Mills, Chester, Lovegrove, Watts.

St Helens: Wellens, Gardner, Gidley, Talau, Meli, Pryce, Long, Cayless, Cunningham, Graham, Gilmour, Flannery, Wilkin.
Replacements: Roby, Hargreaves, Clough, Fa'asavalu.

Referee: A Klein (London)