Hull KR destroyed city rivals Hull FC with six first-half tries at Craven Park.
A dismal 40 minutes from the Airlie Birds increased the pressure on head coach Tony Smith as two Joe Burgess tries pointed the way for the hosts.
Hull improved after the break as Jayden Okunbor and Cameron Scott scored to give brief hopes of a comeback.
Replacement Kelepi Tanginoa quashed those hopes with another try to make it three straight wins for the Robins.
Hull FC’s fifth defeat in their first six Super League matches keeps them in 10th place, ahead of point-less Castleford and London Broncos.
Rovers paid tribute to legendary forward Phil Lowe, who died earlier in the month, in advance of the game, and in the opening 40 minutes their players did justice to the ex-Great Britain man’s memory.
Hull, having leaked over 50 points in their two previous games, looked to be in for another thrashing from the moment full-back Niall Evalds scored one and then drew the defence to create another for Burgess.
Evalds took advantage of awful Hull FC defence to free Mikey Lewis in space and the England half-back ricocheted out of two more weak tackles for another, with James Batchelor scoring his first try of the season.
Lack of a consistent goalkicker was the only thing holding the rampant Robins back as Jez Litten missed the first four conversion attempts.
Litten, in his 100th club appearance, managed to add the extras to the next two tries, as Burgess sent Peta Hiku over and then added his own second touchdown after Hull’s indiscipline piled more pressure on themselves.
The Black and Whites rallied in the second half and Okunbor charged down Lewis’ kick to race clear and score, while 18-year-old Jack Charles, on as a replacement, engineered another for Scott.
Rovers woke from their brief slumber to re-establish control but Hull FC defended their line much better until fresh replacement Tanginoa charged through two tackles to make sure of a Super League double following their opening-day 22-0 win at MKM Stadium.
Hull KR head coach Willie Peters told BBC Radio Humberside:
“Two different halves – first half was outstanding after it took us 12 or 13 minutes to play like we planned to play, and once we did that we were extremely dominant.
“Our kick-chase got us in good positions with the ball and our talented players took over off the back of that.
“Second half we were okay but then they got the charge-down and I wasn’t happy with how we handled it after that period. The momentum shifted for 15 or 20 minutes when it doesn’t need to.
“That’s a fix-up to work on but to win any derby game is pleasing and to win the way we did was nice.”
Hull FC head coach Tony Smith told BBC Radio Humberside:
“It couldn’t have got much worse by half-time could it? It was a fairly solid start and we went toe to toe for a few sets, which was encouraging, but some of our defence fell way off the cliff.
“It allowed them to run their plays and they have some very good players who can hurt you with the ball, and they did.
“To come in at half-time with that sort of score was pretty demoralising. You could easily throw in the towel and not go out to try to fix things up, so on that count, that’s encouraging.
“The 28 points before that, we have to address that.
“We haven’t been in great form lately and the world is telling us how bad we are. It’s hard for young men to feel confident, go out there and do a great job. We have to toughen up, accept the criticism we are copping and say ‘right, it’s time to stop that’.”
Hull KR: Evalds, Burgess, Hiku, Opacic, Hall, May, Lewis, Sue, Litten, Whitbread, Hadley, Batchelor, Minchella
Interchanges: Parcell, Luckley, Storton, Tanginoa
Hull FC: Hoy, McIntosh, Scott, Sutcliffe, Martin, N. Brown, Smith, Ese’ese, Houghton, Ashworth, Okunbor, Sao, Lane
Interchanges: J. Brown, Charles, Gardiner, Pele
Referee: Liam Moore
