Leeds were ruthless in a superb performance which perfectly demonstrated why they are champions, brushing aside play-off hopefuls Harlequins with relative ease.
It was a case of every move succeeding for the Rhinos, while for ‘Quins it was a case of restricting the Leeds onslaught.
McGuire then sped over for a second, but Quins responded accordingly with a David Howell effort. But Jamie Jones-Buchanan extended Leeds’ lead, Sinfield tagging on the conversion and a further penalty to give the Rhinos an invaluable 20-8 lead.
Will Smith, tipped by coach Brian McDermott to make the end of season Four Nations squad, catastrophically cost his side points with an ambitious pass that sailed out of play on his own 10-metre line.
From the resultant scrum, the ball was spread out to Scott Donald who was adjudged to have got the ball down just in time before his foot hit the whitewash. Replays showed that Donald made it by less than a millisecond.
Lee Smith ended a sublime sweeping move to score Leeds’ respective seventh try, while Sinfield maintained an 100% record with the boot, converting his eighth goal.