Bristol blew their big chance to go back to the top of the Guinness Premiership after being ambushed by in-form Harlequins at the Stoop.

Fly-half Adrian Jarvis drilled over five penalties to clinch a fifth league win in six games for Quins, who will see the victory as a major boost to their own play-off ambitions.

David Lemi scored the game's only try - an interception effort in the first-half - and Jason Strange added a penalty for the visitors.

The alarm bells will be ringing for Bristol boss Richard Hill, whose side might have taken advantage of a slip-up by leaders Leicester earlier in the day to return to the summit.

Without England man Shaun Perry at scrum-half, they looked short of direction and their back-row was comfortably outplayed by the outstanding trio of Andre Vos, Paul Volley and Nick Easter.

Quins may have their own problems - midfield pair Stuart Abbott and Andrew Mehrtens were missing, as was leading try-scorer David Strettle - but they were the livelier of the sides in an entertaining opening quarter.

Jarvis fired them in front with a third minute penalty, Strange levelled two minutes later and both sides moved the ball to create scoring chances.

Bristol full-back Josh Taumololo was tackled into touch a couple of metres short on the left and wing Ugo Monye went close at the other end to set up a long spell of pressure only relieved when opposite number Lee Robinson broke out.

In the end, it was an error that created the only try of the game.

Quins were attacking 10 minutes before the interval after a Mike Brown break but then threw the ball straight to Lemi and the Samoan ran 80 metres to score.

Jarvis pulled back three points with his second penalty five minutes later, when Bristol were penalised for hanging on to Tani Fuga on the ground, but he missed from in front of the posts immediately before half-time to leave his side trailing by two points.

Harlequins built up a head of steam after the break, though, and forced Bristol to concede ground and a string of penalties.

Jarvis punished them with successful shots at goal in the 52nd and 57th minutes, the latter after the visitors were reduced to 14 men when flanker Joe El Abd was sin-binned for straying offside at the breakdown once too often.

It needed an important block from Vos to deny Strange a drop-goal chance on the hour and Jarvis was able to nudge his side seven points in front with a fifth penalty 10 minutes from time.

A converted score would have given Bristol a share of the points but they were short of precision in the final minutes and unable to find a way through a defence marshalled superbly by flanker Vos and Easter.