There was nothing to choose between these two sides for almost an hour, but it was Harlequins who pulled away in the final quarter. In doing so, they put last week's 40-point thrashing at Huddersfield firmly behind them.
Quins had to battle more than their share of injuries, and some refereeing decisions that went against them.
"For us to overcome that after the spanking last week was a real team effort," said their delighted coach, Brian McDermott, after seeing his side climb to fifth in Super League, one place behind Hull.
After a pre-match downpour Hull gained the early advantage through Danny Tickle's penalty. Quins grafted their way into the game after that and they took the lead with the game's first try, after 27 minutes. Chad Randall, who was at the heart of much of their best work, ran from dummy-half on the last tackle and Tony Clubb ran in at an angle to take his pass for a score which Danny Orr converted,
Luke Dorn then made a mess of a play-the-ball and Hull equalised, the damage being compounded by Quins conceding a penalty for dissent and the visitors taking advantage by working the ball to the left for Kirk Yeaman to touch down.
In a gritty, no-frills manner perfectly suited to the conditions, Quins put Hull under pressure from the start of the second half. They regained the lead when Jason Golden got over from close range for his first try for the club, but Hull levelled the scores in controversial fashion. Craig Hall got the benefit of a desperately close offside decision as he chased Chris Thorman's kick, Jon Wells missed completely with an attempt to clear the ball and Hall followed up to get the vital touch.
Either side could have gone on and won, but it was Quins who seized the initiative. They deserved something when Orr kicked straight from a scrum, but an evil bounce beat Dorn. A penalty for ball-stealing gave them a narrow advantage before the influential Randall's 40-20 kick yielded the position from which David Howell got over for the crucial try.
The impressive Orr kicked another penalty, given for the Hull markers not standing square, making it five from five attempts for the evening.
Perhaps the best illustration of the determined attitude that saw Quins home, however, was the way that in the last minute, and with the game won, Luke Gale and Clubb got across to tackle Tom Briscoe into touch when a Hull try seemed certain. That is the type of thing that suggests there will be plenty more home wins at The Twickenham Stoop this season.
Harlequins: Wells; Melling, Clubb, Howell, O'Callaghan; Dorn, Orr; McCarthy-Scarsbrook, Randall, Ward, Temata, Mbu, Purdham. Substitutes used: Haggerty, Gale, Heckenberg, Golden.
Hull: Hall; Calderwood, G Horne, Yeaman, Briscoe; R Horne, Thorman; Dowes, Berrigan, Cusack, Tickle, Manu, Radford. Substitutes used: Houghton, Lee, Moa, King.
Referee: R Silverwood (Mirfield).