Glen Jackson's conversion of an injury-time try by hooker Schalk Brits - awarded on the video referee's approval - broke Northampton hearts and sent Saracens to Twickenham on May 29. Jackson also added the extras to earlier tries by full-back Alex Goode and wing Chris Wyles as Saracens held their nerve while Saints imploded during the closing seconds by failing to manufacture a drop-goal chance for Stephen Myler.

Tries in each half by props Soane Tonga'uiha and Brian Mujati, together with three penalties from Myler, looked to have done enough for Northampton. Tonga'uiha, who was destined to join Saracens next term before agreeing fresh terms with Saints - it sparked a bitter war of words between the clubs - helped pick Northampton up by their boot-laces after being outplayed for much of the contest.

Saracens were a far more adventurous side, but once Saints got a grip up-front and began exerting a vice-like grip through their forwards there seemed no way back for the visitors. Goode, somehow overlooked for England's summer tour to Australia and New Zealand next month, was easily the game's most accomplished performer.

He outshone Northampton's revered back-three of Ben Foden, Chris Ashton and Bruce Reihana by showcasing a dazzling skills-set, and his performance ultimately reaped the reward it deserved as Saracens booked a Twickenham appointment with Leicester or Bath.

Northampton, beaten by Saracens on home soil 22 days ago, fielded South African Mujati in the tighthead role instead of Scotland international Euan Murray, whose religious beliefs mean he does not play on a Sunday. The visitors, meanwhile, were boosted by Goode's recovery from a thumb injury. Goode reclaimed his familiar number 15 shirt, which meant Wyles switching to the wing instead of Richard Haughton.

The clubs' fifth meeting this season followed an acrimonious month marred by the Tonga'uiha affair, in addition to Northampton criticising Saracens' victory celebrations at the Gardens three weeks ago. Early exchanges were inevitably feisty, with top English referee Wayne Barnes wasting little time exerting his authority on what was expected to be an explosive contest.

It took Barnes barely seven minutes to brandish a yellow card, and Saracens could have no complaints after their flanker Jacques Burger was sin-binned. Saints number eight Roger Wilson's defence-splitting run ended with him being hauled down by Burger, but when the South African blatantly prevented quick possession being recycled, he left Barnes with little option.

Myler kicked the resulting penalty, yet Saracens made light of their temporary one-man disadvantage by conjuring a stunning try in his absence. Brits made a decisive midfield break, finding lock Mouritz Botha in support, before Jackson found Goode, who finished in clinical fashion. Jackson added the conversion, and with Saints conceding penalties at alarmingly frequent intervals, Saracens began to establish a degree of control.

They regularly looked to free game-breaking runners like Burger, Botha and Brits, while Goode provided a touch of class behind. Saints eagerly looked for Ashton - the Guinness Premiership's top try-scorer this term - to orchestrate their attacking game, but Saracens remained dominant until they were stung on the stroke of half-time.

An intense physical encounter began to take its toll, with players from both sides requiring treatment, yet the pain was all Saracens' when Tonga'uiha punished them. The heavyweight Tongan rumbled his way along the touchline, smashing would-be Saracens defenders out of his path, and he touched down following a 30-metre break that gave Northampton an 8-7 interval advantage.

Myler quickly extended the lead with his second penalty, only for Saracens to hit back through another slick score. Goode capitalised on Saints centre Jon Clarke losing possession, and it was lock Hugh Vyvyan who freed Wyles with a perfectly-delivered pass. Jackson's conversion made it 14-11, yet Northampton rapidly drew level courtesy of a mammoth Myler penalty strike from wide out just a metre inside Saracens' half.

And it gave Saints momentum, with their forwards keeping possession at close quarters to drive Saracens back and enable Mujati to touch down underneath a pile of bodies. Although Myler missed the conversion, Northampton entered the final quarter holding a five-point lead and knowing that one more score would leave Saracens with a mountain to climb.

But Saracens gave it everything in pursuit of victory, and their patience was rewarded when Brits stormed across for a try before Jackson's conversion saw them home amid dramatic scenes.