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Kick-off: 14:30 BST
Leigh and Catalans sealed their places in semi-finals after their respective victories on Friday
Hull KR lose talismanic half-back Mikey Lewis to suspected groin injury after 15 minutes, but motor into lead despite his absence
Hull FC 12-30 Hull KR
Image source, SWPixKelepi Tanginoa is head down as he tries to bulldoze his way toward the line about 10 metres out.
Will Pryce comes in heavy and high and concedes the penalty.
It gives Hull KR the chance to add to their lead from the kicking tee.
Hull FC 12-30 Hull KR
The captain's challenge is successful, with Hull KR now camped right on the line.
Hull FC 12-30 Hull KR
Chances have been coming in waves for both sides since the break.
Hull KR were rocked by those tries, but they might be about to get the ball back a few metres from the Black and Whites line.
Tyrone May tries to kick through, but it crashes into a Hull FC body before being regathered.
The Robins challenge to re-set the tackle count arguing that the ball was played at.
Herman Ese'ese, goal Pryce
The derby has been transformed in the blink of an eye.
There is a reason that Herman Ese'ese is called The Herminator.
He takes a pass about 10 metres out, busts through one attempted tackle, evades another one or two and gets the ball down despite having Hull KR defenders hanging off him.
Will Pryce chips away at Hull KR's lead by landing another conversion.
It's game on!
Ese'ese scores for Hull FC against Hull KR
Hull FC 6-30 Hull KR
Staggering! Hull FC might just have come up with another quick try.
The comeback might very well be on.
Lewis Martin, goal Pryce
Hull FC needed this!
With their first attack of the second, the Black and Whites hit back with a try through Lewis Martin.
Jordan Rapana found the prolific winger with a looped pass out to the wing.
Will Pryce converts with his first points for Hull FC
Can this spark the hosts to life?
'Young hope' Martin scores Hull FC's first try
Hull FC 0-30 Hull KR
Robbie Hunter-Paul
Former New Zealand international on BBC One
Hull FC was on the backfoot defensively and then this happens.
Hull FC 0-30 Hull KR
John Kear
Former Bradford Bulls head coach on BBC One
He's created tries, kicked goals and he's scored tries.
He backs his pace against a disjointed Hull FC defence.
30 points for a substitute is sensational.
Jez Litten, goal Jez Litten
Hull KR stretch their lead further.
Jez Litten grew up as a Hull FC fan, his cousin Davy is with the Black and Whites this afternoon, but he has just landed another huge blow on his former side.
He is only a few metres out as he looks to his left for a pass, he throws a dummy and then puts the foot down and rips through a gap in Hull FC's defence to score his first try of the day.
He then steps up to convert his own score to make it 30-0.
Challenge Cup: Jez Litten scores Hull KR's fifth try against Hull FC
Hull FC 0-24 Hull KR
The BBC One cameras turn to focus on Hull FC head coach John Cartwright in the stands.
His stern look gives nothing away, but with his side now 24-0 down against derby rivals Hull KR his mind must be racing.
Hull FC 0-24 Hull KR
Robbie Hunter-Paul
Former New Zealand international on BBC One
The numbers are fine for Hull FC but when you gift the ball to the opposition, everything becomes scrambled.
There are actually four on four with defenders there. Hull KR hold their field position so well and they will punish you.
Joe Burgess, goal Jez Litten
This might just about be game over...
Another error from Hull FC in their own half gifts the ball back to the Robins and they ruthlessly take full advantage.
The ball is shifted effortlessly out to the left where Oliver Gildart finds Joe Burgess waiting to grab his second try of the day.
Jez Litten turns it into a 24-point lead with his conversion.
Hull FC have Everest to climb if they are to upstage the Robins now.
'Clinical' Hull KR side score their fourth try of the match
Hull FC 0-18 Hull KR
There is word coming out of the Hull FC camp that Jordan Lane's day is done.
The second-rower ended the first half with his arm in a sling.
Less surprising is confirmation that Mikey Lewis is also not going to make it back to the pitch for the Robins.
Hull FC 0-18 Hull KR
A few tackles into the second half and Yusuf Aydin comes slamming into Jai Whitbread with a big hit.
The message that comes with it is that Hull FC mean business as they try rescue this Challenge Cup tie.
Hull FC 0-18 Hull KR
The two teams have emerged from the player's tunnel for the second half.
A huge 40 minutes await.
HT: Hull FC 0-18 Hull KR
Kevin Brown
Former England international on BBC One
Neither side took control. It took the adversity away when Mikey Lewis went off to spark KR into some sort of control to dominate.
It was Hull KR who settled down as Lewis went off. The message went on to just calm it down and it really worked.
HT: Hull FC 0-18 Hull KR
Jamie Peacock
Former England captain on BBC One
These two are top of the league, the quality was down in the first 20 minutes.
But sticking to the gameplan from KR got them through in the final 20 minutes. They've managed to grind out three tries and it shows why they're top of Super League.
HT: Hull FC 0-18 Hull KR
John Kear
Former Bradford Bulls head coach on BBC One
It was nip and tuck for 20 minutes.
But on the back of losing a stellar player in Mikey Lewis Hull KR have reorganised and had a stonking last 20 minutes of this half.
Hull FC 0-18 Hull KR
Image source, SWPixHull KR stunned hosts Hull FC with quickfire tries from Tom Davies and Joe Burgess.
A third from Jack Broadbent just before the break now has the hosts on the ropes.
And the Robins managed to do all that after losing star man Mikey Lewis to injury.
Hull FC 0-18 Hull KR
The packed Hull FC crowd have been waiting all afternoon for this.
Will Pryce displays some of the flash and guile that has made him such a high-profile addition.
The Black and Whites go searching for their first try of the game in the final seconds of the first half, but the kick through runs dead.