The Super League leaders were beaten for only the third time this season by a Harlequins side containing seven of their own, home-produced players. One of them, the wing Will Sharp, scored two of their tries as the Londoners claimed a famous victory.
It looked ominous for Quins when Jamie Peacock scored a decidedly soft try after three minutes, simply running through a gap from Matt Diskin's pass. Their response was admirable, however, with Scott Hill and David Howell handling smoothly for the Nigerian-born Sharp to score the equalising try.
Hill, plagued by injury for much of his 18 months in London, was having a major influence on proceedings. After 16 minutes, he took a pass from Chad Randall and found a route to the line to put Quins ahead.
Leeds were visibly rocked and were producing little of their usual expansive handling, although they were denied a Rob Burrow try for an obstruction decision back down the field. That gave Henry Paul the chance to land his third goal for Harlequins for an eight-point lead.
Much of the home side's good work was then undone by a horrible mistake by Chris Melling, who fumbled Jordan Tansey's kick under no pressure whatsoever. That gave the Rhinos their invitation and a wonderful pass from Burrow sent Scott Donald over in the corner, with Kevin Sinfield's second goal reducing the gap to two points.
Quins kept pressing after the break and after the debutant, Lamont Bryan, drew a penalty from Keith Senior, Randall scrambled over to stretch their lead. Tony Clubb could have stretched it further but lost the ball going over the line. That just left the door ajar for Leeds, with Danny McGuire's long break setting up the position from which Senior collected Burrow's pass to go in.
The tension showed when Senior and Quins' Louie McCarthy-Scarsbrook went to the sin bin after a mêlée involving most of the players. The penalty went to Quins with Paul landing his fifth goal. It was a perfectly judged kick from Hill that seemed to have clinched it, with Sharp timing his run equally well to claim his second try.
Burrow got one back for the Rhinos, but Sinfield hit the post a second time and Quins had enough of a cushion, even after Donald scored with four minutes to play.
"It's been a great week," said the Harlequins coach, Brian McDermott, who could not have wished for a better vindication of his decision to agree a new three-year contract.
Harlequins: Melling, Bryan, Clubb, Howell, Sharp, Hill, Orr, Temata, Randall, Ward, Worrincy, Mbu, Paul. Substitutes used: McCarthy-Scarsbrook, Rinaldi, Haggerty, Janowski.
Leeds: Webb, Smith, Ablett, Senior, Donald, McGuire, Burrow, Leuluai, Diskin, Bailey, Peacock, Ellis, Sinfield. Substitutes used: Jones-Buchanan, Scruton, Tansey, Worrall.
Referee: A Klein (Keighley).Reuse content