Pre-match predictions of a finely-balanced contest between two of the Zurich Premiership's form teams were rubbished at Franklin's Gardens as Northampton destroyed Gloucester with a stunning first-half display.

Saints racked up a commanding 27-0 interval lead as the Cherry and Whites were taken to the cleaners up front, giving Wayne Smith's men a glut of possession which they used to good effect.

And it was fortunate they did take their chances - they were forced to play the entire second period with 14 men after Mark Robinson was sent off for fighting four minutes into injury time.

The former All Black reacted violently when Shane Drahm and Duncan McRae - the player responsible for leaving Ronan O'Gara in a bloody mess during the 2001 Lions tour - exchanged blows.

A mass brawl errupted - virtually all 30 players were involved - and following a lengthy consultation with his touch judges, referee Robin Goodliffe brandished Robinson with a red card while Gloucester's Adam Eustace was dispatched to the sin-bin.

Robinson's exit meant Northampton were under the cosh for virtually the entire second-half - they were even reduced to 13 men following Mark Tucker's sin-binnng - and Gloucester took full advantage by running in tries through Andy Hazell and James Forrester (2).

It was a stunning defensive effort from Saints who were constantly under siege and also had man-of-the-match Andrew Blowers yellow carded in the dying moments, but such was their first-half superiority they could soak up the losses in personnel.

Their tries arrived before the break through Chris Budgen and John Sleightholme, Bruce Reihana chipped in with two penalties - but the star of the show was Drahm who displayed his usual accomplished touch at fly-half and booted 14 points.

Drahm's pinpoint kicking has swept him to the top of the Premiership's points scoring chart this season and he made no mistake when Gloucester drifted off-side in the third minute, slotting a long-range penalty between the posts.

The Australian, who arrived at Franklin's Gardens from relegated Bristol over the summer, added another three points as the Cherry and Whites' indiscipline was further punished by the referee.

Spanish winger Oriol Ripol was proving a menace down the left flank and he made the initial break which led to Saints' first try, surging downfield after collecting his own chip ahead and winning a penalty which Drahm used to find touch in the corner.

Good work at the line-out saw the ball fed to lock Matt Lord who began the drive forward from 10 metres out before prop Budgen bundled his way over, with Drahm adding a tricky conversion and two further penalties.

Gloucester's problems deepened in the 32nd minute when Drahm was flattened by a late challenge from Andy Hazell and Goodliffe wasted no time in brandishing a yellow card for the flanker.

Drahm picked up an injury during the incident and although he was able to remain on the pitch, he handed the kicking duties over to Reihana who cannoned over a simple three points, but failed to convert Sleightholme's 37th-minute try.

Full-back Nick Beal initiate the move after Northampton secured quick possession at the breakdown and he turned Goodridge inside and out before finding former England winger Sleightholme who dived over.

The match then erupted into violence following a flashpoint between Drahm and McRae, and Goodliffe took the necessary action, although in truth any number of players could have been punished.

Gloucester were on top after the break as they camped themselves in the home side's 22, but their line-out work close to Saints' danger zone was sloppy and Beal managed to scramble the ball to safety.

The Cherry and Whites continued to apply plenty of pressure and Northampton could not hold out forever, finding themselves stretched to breaking point to allow Hazell to charge home - Henry Paul added the extras.

Saints were reduced to 13 men in the 66th minute when Tucker was sin-binned for a professional foul and Gloucester capitalised when substitute Forrester concluded a powerful forward drive.

Forrester came up the ball again following a virtually identical try on the left, but Paul missed both conversions and Northampton put the match beyond doubt with Reihana's second penalty.