Harlequins 46 Leeds Carnegie 11: Leeds pay heavy price for the sins of Clark as Quins run riot

Four of the hosts' six tries came in a nine-minute spell after 20-year-old Leeds flanker Calum Clark was sin-binned in the 61st minute for a blatant late challenge on Quins playmaker Nick Evans.

"Discipline is always key and we had a couple of bits of ill-discipline down to the fact you've got a young player trying his best and trying everything he can," said Back.

"But he did some silly things and the 10 minutes that player was on the bench was catastrophic."

But former England flanker Back insisted the heavy defeat was nothing more than "a blip".

He said: "It's disappointing for the squad but it's not a reflection of where Leeds Carnegie rugby are. That won't happen again – we can't afford it to happen again.

"We're almost guilty of trying too hard. The players are desperate to consolidate our position in the Premiership.

"They played as individuals towards the back end of that game and made errors. Quins were smart and streetwise in the dark arts but it's one we'll learn from.

"London Irish is our next objective but today was very much a blip. We've not lost our shape. We've kept our composure. Physically, we've competed. We had a platform to play off, however we've made too many mistakes chasing the game.

"Players tried too hard to remedy it for themselves rather than sticking to the plan."

The bonus-point victory kept Harlequins' outside chances of a top-six finish and Heineken Cup qualification alive but director of rugby Conor O'Shea is not getting carried away.

He said: "We're up to seventh but it's a big ask – Saracens away, Leicester away and Sale at home."

O'Shea, who described Clark's sin-binning as "helpful", continued: "The previous week we created a lot of try-scoring opportunities but didn't take them.

"This week we were on the wrong end of a 17-11 penalty count which for a team that was dominant is pretty surprising to say the least but we can only control what we have ourselves.

"I thought we were quite passive in the first half in our defence but, not being patronising in any way, Leeds are a good rugby side and, as Backy said to me, that's the first time that has happened to them this season.

"Sin-binnings are a massive part of the game and we were ruthless in that period and scored the tries – we have a lot of gas in our back line."

Full-back Mike Brown scored twice for Quins and wingers Tom Williams and David Strettle, centre George Lowe and replacement hooker Chris Brooker also touched down.

Former All Black Nick Evans added 14 points, with two penalties and four conversions, with his replacement, Rory Clegg, converting the final try.

Leeds replied with two penalties from fly-half Ceiron Thomas and a last-minute consolation try from No 8 Alfie To'oala. They failed to capitalise on the numerous inroads powerful Fijian centre Seru Rabeni made into the defence as they suffered their third successive defeat, following the mini-revival which has taken them off the bottom of the table.

Evans kicked Quins ahead in the seventh minute with a 40-metre penalty after Leeds were brought back for a late challenge on full-back Mike Brown after he fielded a kick.

Six minutes later, the opportunist thinking of Evans created the first try. Taking a quick lineout, the Kiwi fly-half found full-back Brown, who scythed through the middle, drawing the defence before throwing a long pass which sent winger Williams in unchallenged at the corner.

Rabeni was proving a handful, crashing through three tackles in one Leeds attack and beating two men in the next.

But Harlequins hit back and the pace of Williams took him past three defenders before Leeds conceded a penalty in the 25th minute, landed by Evans to put Quins 13-0 ahead.

Leeds opened their account with a penalty from Thomas three minutes later after a Quins scrum infringement.

Returning England No 8 Nick Easter provided stability at the base of the scrum for Quins.

Leeds tried to get back into the game but Leigh Hinton lacked support after a piercing run and Quins hit them on the break to score again after 52 minutes, Brown picking up and forcing his way over after Strettle was stopped just short by Hinton.

Thomas landed his second penalty for Leeds in the 60th minute but their hopes of salvaging anything were ended a minute later when lock Clark, bound for Northampton at the end of the season, was yellow-carded for a wickedly late challenge on Evans after he had kicked clear.

Harlequins immediately cashed in on their numerical superiority with four tries in the space of nine minutes.

Evans and Strettle combined to send in centre George Lowe before the depleted Leeds pack proved no match for a huge 25-metre forward drive which took Brooker over.

Brown's second try came in the 69th minute. Williams had his shirt tugged by Hinton as he chased his own kick but Brown won the chase to get a hand on the loose ball.

Strettle then showed his pace, outstripping the defence on a run from halfway, for the sixth try, before To'oala's reply a minute from time.

Harlequins: Brown, Strettle, Lowe, Turner-Hall, Williams, N Evans, Care, Jones, Fuga, Andress, Percival, Robson, Guest, Skinner, Easter. Replacements: Mordt for Turner-Hall (69), Clegg for N. Evans (69), Dickson for Care (69), Croall for Jones (64), Brooker for Fuga (41), Johnston for Andress (53), Stevenson for Robson (58), York for Guest (49).

Leeds Carnegie: Hinton, Fa'afili, Rabeni, Barrow, Blackett, Thomas, Mathie, Nilsen, Gomez, Lund, Wentzel, Clark, Fourie, To'oala, MacDonald. Replacements: Welding for Barrow (60), Gomarsall for Mathie (68), Titterrell for Nilsen (58), Swainston for Gomez (58), Ford for Wentzel (73), Oakley for Clark (77), Myall for Fourie (73), Hardy for MacDonald (64).

Referee: D Richards (RFU).

Scorers

Harlequins – Tries: Williams, Brown 2, Lowe, Brooker, Strettle. Cons: N Evans 4, Clegg. Pens: N Evans 2.

Leeds –Try: To'oala. Pens: Thomas 2.