Danny McGuire and Brent Webb claimed two tries apiece as Leeds Rhinos condemned Harlequins coach Brian McDermott to a losing return to Headingley Carnegie.

Great Britain stand-off McGuire crossed the line twice in the first half to sandwich a score from New Zealand Test full-back Webb and help Leeds establish a 20-4 interval advantage.

Webb emulated his team-mate three minutes after the restart when he completed his brace but Rhinos could never rest easy against a spirited Quins side who dominated for long periods in the second half.

The Londoners were ultimately left to pay for a dismal opening period which saw Leeds power 12-0 ahead with little more than 10 minutes played.

McDermott, the former Bradford prop who quit his post as assistant to Rhinos coach Tony Smith midway through last season, must have feared the worst at that point.

Quins only had themselves to blame for the score which handed Leeds an eighth-minute lead.

Chris Melling, a player whose pedigree has never been in doubt having risen through the ranks at Wigan before moving to the capital during the close-season, inexplicably dropped the ball 20 metres from his own line.

McGuire needed no second invitation to collect possession and scamper over for the easiest touchdown of this or any other season.

Leeds began to move quickly through the gears, keeping the ball at every opportunity with McGuire at the heart of all their most promising attacks.

And they extended their lead in the 11th minute when McGuire's kick laid the platform for a move which involved Gareth Ellis and Matt Diskin and culminated in Webb adding the finish.

Skipper Kevin Sinfield added his second conversion to put Leeds 12-0 ahead and seemingly in total control.

But credit to Harlequins - and Melling in particular - for the response which came Leeds' way.

The former England Academy player produced a stream of crucial tackles and, after a spell of sustained pressure midway through the first half, he was on hand to collect Chad Randall's pass and crash over the line.

Henry Paul failed to add the extras and, with McGuire and Rob Burrow again proving an irresistible force, Leeds had more than enough power to unlock the Londoners' defence.

So it proved in the 32nd minute when Burrow's meticulous dummy running gave Leeds the field position which allowed McGuire to dart through a gap in Quins' rearguard for his fourth try of the season. Leeds' half-time advantage was a commanding one at 20-4 and it took them just three minutes to extend that lead when Ashley Gibson's crafty kick was pounced upon by Webb.

Sinfield claimed his fifth goal from as many attempts but once again Quins came back strongly.

Again that it was no small part down to Melling, who was stopped short of the line in the 51st minute, but from that set of six Mark McLinden produced an exquisite long pass to Matt Gafa in the right corner.

He touched down and Paul added the two points to reduce the deficit to 16 points and encourage hopes of an improbable comeback.

It never came as Sinfield added another penalty in the 72nd minute to put Leeds home and dry to ensure Paul Sykes' late try - converted by Rob Purdham - was no more than consolation.