Hull (10) 17
Tries: Raynor 2, Washbrook Goals: Tickle Drop: Dykes
Hull KR (10) 22
Tries: Fox, Fitzhenry, Walker, Webster Goals: Cooke 3
By Julian Shea
BBC Sport at the Millennium Stadium
Webster scored with just four minutes remaining
Jake Webster's late try earned Hull KR victory over city rivals Hull at Cardiff's Millennium Stadium.
Gareth Raynor's try on 48 seconds got things off to a thrilling start and both sides had chances to score before Rovers' winger Peter Fox went over.
Daniel Fitzhenry extended the lead but Raynor scored his 100th Hull try.
Danny Washbrook and Chev Walker traded tries as the teams remained level until Adam Dykes's drop-goal, but Webster's score won it for Rovers.
The smoke and smell from the pre-match fireworks had not even cleared when Raynor opened the scoring, narrowly eluding Fox's tackle to crash over in the left-hand corner after Craig Hall¿s great build-up work.
Rovers looked stunned by the early setback but should have got on the scoreboard when Walker knocked on at the play-the-ball in an attacking position.
He soon made amends though when he set up a Fox try and six minutes later Rovers' lead was stretched when Stanley Gene's optimistic pass found Fitzhenry in the corner.
Raynor bagged his second just before half-time, when Fox's attempt to control Richard Whiting's kick-through gifted him possession.
Washbrook and Walker scored for either side after the break as the teams remained locked in a fierce tussle, but Paul Cooke looked to have given Rovers the edge when he attempted a drop-goal from right in front of the sticks.
But to the delight of the Hull fans he missed, lifting the pressure off the Rovers attack.
Within minutes play was down the other end of the pitch and Dykes made no mistake with his drop-goal, edging Hull in front.
But with time running out, Ben Galea set up Webster to score and Cooke made no mistake with the conversion.
Hull KR coach Justin Morgan:
"I felt we had it in us to score the try. We took some feedback from Paul Cooke and Ben Galea and they wanted to go for the try.
"We got our just rewards at the end. We kept our composure for the full 80 minutes and put on a really nice play at the end.
"I thought we had a few opportunities that we didn't exploit in the first half. In the second half we had plenty of ball and we looked for a few better decisions.
"Our players showed a huge amount of determination and courage."
Hull coach Justin Peter Sharp on Steve Ganson's decision to penalise Tommy Lee for a knock-on, which led a Hull KR try:
"It was a massive call and I thought it was poor. There is no other way of looking at it.
"There is a lot at stake for clubs and we've got to do better than that.
"All losses hurt but a derby loss hurts even more. But we showed some signs that we're on the mend, I think we can build some momentum."
Hull: Byrne, Sing, Yeaman, Hall, Raynor, Washbrook, Dykes, Dowes, Berrigan, Cusack, Manu, Tickle, Radford.
Replacements: Lee, Whiting, Thackray, Wheeldon.
Hull KR: Briscoe, Fox, Walker, J. Webster, Fitzhenry, Cooke, Murrell, Vella, K Netherton, Mills, Newton, Gene, Galea.
Replacements: Crossman, Fisher, Cockayne, Chester.
Referee: S Ganson (Great Britain)