Hooker Dylan Hartley came off the replacements' bench to score the try which broke the deadlock as Northampton made a winning return to the Guinness Premiership.

Hartley, the only Saints player in England manager Martin Johnson's full squad, had to play second fiddle to Paul Shields when director of rugby Jim Mallender named his squad for the opening match.

But he made an almost immediate impression after replacing Shields in the 48th minute, gratefully accepting a long pass from young scrum-half Lee Dickson and crashing through a tackle before stretching for the touchdown.

The try came after Worcester had been temporarily reduced to 14 men when flanker Tom Wood was yellow-carded for an infringement which allowed Northampton skipper Bruce Reihana to level the scores at 6-6 with his second penalty.

It was a costly offence for Worcester as Mallender also used the break in play to send on Hartley.

Northampton, who stormed through National Division One unbeaten last season for an instant return to the Premiership, capitalised when centre Jon Clarke went in for their second try in the 66th minute

Taking a pass from number eight Roger Wilson, the new recruit from Ulster, following yet another sustained spell of Saints pressure, Clarke had a clear run to the line.

Worcester, with former Australia full-back Chris Latham making his Premiership debut, finally made an attacking impression as hooker Aleki Lutui went through the home defence for a 72nd-minute try, converted by new fly-half Matthew Jones.

But Reihana's third penalty, in the 76th minute, secured a deserved victory for his side.

Before Hartley breached their line Worcester had defended bravely, repelling a wave of Northampton attacks, and their task was made easier by the inconsistent kicking of Reihana.

The full-back missed two straightforward early penalties as well as failing to convert Hartley's try.

Jones, recruited from Welsh side Ospreys, landed the two penalties which put the Warriors 6-3 ahead at the interval.

Worcester, without skipper Pat Sanderson because of a quad injury and winger Marcel Garvey with a hip problem, soaked up all the first half pressure.

Latham provided a confidence-boosting display on his debut and, despite this defeat, could well be a steadying influence to a Worcester side anxious to avoid another relegation dogfight after last season's tussle with Leeds, who went down.

The first clear-cut try-scoring opportunity fell to the Warriors when right-wing Rico Gear kicked ahead but Irish international flanker Neil Best denied him with a good piece of cover play.

The new experimental law variations resulted in a rash of penalties which saw Jones edge Worcester in front.

Saints, with Spencer orchestrating their attacks, stepped up the pressure as half-time approached but Best, a summer signing from Ulster, was denied a try on his first league appearance for Northampton when his touchdown was ruled out because of a forward pass.

Altogether Saints had six new signings in their starting line-up with Mallender fielding Ignacio Fernandez Lobbe and Christian Day in the second row, the back row trio of Best, Wilson and Scott Gray and England Saxons' scrum-half Lee Dickson.

The choice of Dickson ahead of Ben Foden, the high-profile recruit from Sale Sharks who was named on the bench, was something of a surprise but he responded with a lively display, linking well with former All-Black Spencer.

Saints also had Scotland winger Sean Lamont back in league action for the first time since his knee operation last November.

Lamont went looking for the ball but was closely watched by Worcester who denied him any sort of try-scoring opportunity.