David Howell grabbed a crucial late try as Harlequins battled past Hull at the Stoop.
The Australian centre crashed over with less than 15 minutes remaining to decide a bruising encounter between two sides with play-off aspirations.
Quins will be especially delighted with the win after regulars Matt Gafa and Will Sharp withdrew through injury before kick-off.
With torrential rain and a howling wind the game was never likely to be a free-flowing spectacle, and the first half was a war of attrition where neither side took control.
Hull had the early pressure and were rewarded when Danny Tickle slotted a penalty.
But with both sides struggling to find any rhythm, the first quarter was merely punctuated by misjudged kicks by Danny Orr and Chris Thorman on the last tackle.
However, as the half wore on the game began to open up and the hosts took the lead when Chad Randall elected to run on the last tackle, allowing Tony Clubb to power his way through a number of tackles to score.
The lead was short-lived however, as after Gareth Haggerty was penalised for dissent, the visitors spread the ball wide and centre Kirk Yeaman scampered over in the corner.
Tickle missed the conversion, meaning the sides went in all square at the break.
Both sides showed far more attacking intent in the second period and it remained a tight contest.
The hosts regained the lead minutes after the restart when Jason Golden burrowed his way over, but Hull bounced back when Craig Hall grounded Thorman's kick through after confirmation from the video referee.
But as the clock ticked down it was the Londoners that stepped things up and, after Orr booted a penalty, Howell crashed over from Randall's pass to open an eight-point lead.
Orr then kicked another penalty to wrap things up.