Harlequins shunted Leeds closer to relegation with an emphatic seven-try 51-18 victory that leaves the Yorkshire club increasingly adrift at the foot of the Aviva Premiership Rugby.
The home side earned a bonus point by scoring four tries long before the end, a haul that moves them up the table and a step closer to the pre-season ambition of rugby director Conor O'Shea, who insisted they were potentially a title-chasing team.
For Leeds, though, the winter will be long and hard as they battle for survival.
Harlequins began the day ninth in the table having managed only a draw from their three previous Aviva Premiership Rugby games.
Leeds came to the Twickenham Stoop still seeking their first league win of a difficult season which has seen them harvest only three losing bonus points from eight defeats.
And it was the visitors who reacted the sharper in freezing weather, punishing a sloppy start by their hosts who presented Leeds possession from the kick-off. Under pressure, Quins went offside and referee Martin Fox awarded the game's first penalty, coolly drilled over by Leeds fly-half Ceiron Thomas.
It took only four more minutes to see why Leeds are struggling, however. Having turned over Quins ball, it came to Rhys Oakley whose attempted pass to his left was intercepted by Chris Robshaw, afforded a free run-in for a try which was converted by Nick Evans.
They enjoyed a let-off on 11 minutes when pressure earned a penalty, only for the usually ruthless Evans to send his kick crashing against the left-hand upright and back into play.
There was no let-off on 17 minutes, however. Mike Brown broke out from the back and managed to off-load for Robshaw to find loosehead Joe Marler. The prop attacked the Leeds defence, drew two men and flipped a fine ball inside for scrum-half Karl Dickson, who scored at full pelt.
Evans again converted and added a penalty on 21 minutes as Leeds grew visibly more fragile under pressure. The sole consolation for under-pressure head coach Neil Back was that his players were up for the battle, if lacking the necessary quality to actually win it.
That determination paid off when Thomas added his second penalty of the game on 27 minutes after Quins drifted offside.
Evans replied in kind four minutes from half-time, but his next score was extra-special. Quins retained possession for phase after phase until Brown collected a ball thrown over his head by Dickson from the Leeds line which changed the point of attack, and Evans took Brown's inside pass to dart over by the post before converting his own try.
The problem facing the Leeds management remains their need for someone or something to lift them, to give the players real belief in themselves. After a decent start, it took only one intercepted pass to leave collective chins on the floor and by the break, the game was over as a contest.
All the more so when Tom Guest stormed forward six minutes after the break and simply shrugged off two weak tackles to score. Evans added the conversion as the crowd celebrated the bonus-point fourth try.
Credit Leeds, therefore, for battling back to score a try on 50 minutes when Lee Blackett finished off a strong move involving lock Tom Denton, whose drive set up the opportunity as Harlequins backed off. Thomas missed the conversion.
The problem was that Leeds needed to suddenly discover title-winning form just to close the gap enough to claim a losing bonus point, such was the superiority of their hosts when they chose to raise their game.
They did just that 10 minutes from time when Dickson scurried up the left, and kept heading for the line as Leeds backed off, expecting an inside pass. When they did decide to go for him, Dickson promptly lobbed the ball inside for Mike Brown to finish in style.
Once again, Quins were caught out just after scoring. A break out saw Blackett score his second try of the game, Thomas converting. It showed the team's character at a time when it would have been easier to try to wind down the clock.
Ross Chisholm scored a solo try three minutes from time, helped by a lack of Leeds tackling, and Rory Clegg kicked the conversion.
Dave Moore barged over for the final try, but this time Clegg missed the conversion.