Harlequins continued their drive for a top-four Guinness Premiership place with maximum points from a fourth win in five games.

However, Bristol - themselves seeking a their third successive victory - pressed the visitors hard and were denied a losing bonus point from the fifth encounter between the teams this season.

Bristol, 3-1 up in the mini-series following two Heineken Cup successes and a pre-season friendly win, were aiming to avenge their 24-18 defeat at Twickenham Stoop in the Premiership in October.

The hosts made five changes from the side which triumphed at Newcastle last Sunday with David Lemi on the left wing, Neil Brew back in the centre after from injury, Nathan Budgett at lock, Alex Clarke at loosehead prop and Andrew Blowers at openside flanker.

Harlequins also made changes to the side which defeated Bath at home with former Bristol lock Ollie Kohn back at his former club and Jordan Turner-Hall at inside centre.

Bristol supporters also had the opportunity of seeing Quins fly-half Adrian Jarvis, who moves to Bristol in the summer.

The game was less than five minutes old when referee David Rose, working on the advice of his touch judge, had to exert his authority when Bristol prop Jason Hobson was penalised for throwing a punch in a tussle on the ground with Quins prop Ceri Jones and hooker Tani Fuga.

Quins took the lead when number eight Tom Guest passed for left wing Charlie Amesbury to score the game's first try.

Jarvis, kicking into the wind, failed with his conversion attempt but Bristol number 10 Ed Barnes showed his kicking skills with a long-range penalty which quickly reduced the arrears.

Bristol scored a try when Lemi found wing Tom Arscott, who stepped inside full-back Mike Brown to touch down.

Barnes missed his touchline conversion and also failed with a simple penalty after Jarvis had levelled the scores with a 22-metre kick.

After a delay for treatment to Quins flanker Chris Robshaw, Barnes missed another penalty attempt to leave the score 8-8 at the interval.

Robshaw was replaced by Chris Hala'ufia - and the visitors were reduced to 14 men within five minutes of the restart when Jarvis was yellow carded for persistent infringement.

Bristol were awarded a series of penalties and opted each time to kick for the corner, while Rose warned skipper Will Skinner about his side's future conduct.

At the next catch and drive Quins again infringed - and Rose awarded a penalty try which Barnes converted.

Chris Malone, who had a brief spell at Bristol in the 2003-04 season, came on as a blood replacement for Amesbury and reduced the arrears to four points with a penalty.

Quins regained the lead as the game went into the final quarter with Brown stretching for the line after taking the scoring pass from scrum-half Danny Care.

Jarvis converted from out wide but missed a long-range penalty before being replaced.

Brown was stopped just short of the line but the forwards went to work and drove over - with lock George Robson credited with the try.

Quins sealed the game and secured a bonus point when Robson intercepted a pass from Bristol skipper Matt Salter on the half way before scoring in the left corner.