Northampton (7) 20
Tries: Dowson, Diggin Cons: Myler, Geraghty Pens: Geraghty 2
Worcester (17) 17
Tries: Benjamin, Horstmann Cons: Walker 2 Pen: Walker
Saints captain Dylan Hartley drove his side on to victory
Paul Diggin's try with two minutes left saw Northampton snatch victory and deny Worcester a surprise away win to open their Guinness Premiership campaign.
The Warriors went 17-0 ahead inside the opening half-hour with tries from Miles Benjamin and Kai Horstmann.
But Phil Dowson's try before the interval reduced Saints' deficit.
Two penalties from Shane Geraghty, taking over from the injured Stephen Myler, made it 13-17 and their pressure told when Diggin went over late on.
Geraghty added the conversion to seal a memorable league debut for the former London Irish midfielder after his summer move.
The England prospect was switched from inside centre to fly-half and handed the goal-kicking responsibilities 12 minutes into the second half after Myler was forced off with a right ankle injury.
But his two well-struck penalties just after the hour gave Saints the momentum to go on and claim victory, while Warriors fly-half Willie Walker - who had earlier converted both tries and added a penalty - missed with two vital second-half opportunities.
Walker was then sin-binned with eight minutes left as a direct result of the constant Saints pressure.
The hosts always looked capable of making the extra man count, but Geraghty's smart cross-kick to the right corner with five minutes left just eluded the lurking Dowson.
But a well-worked move with two minutes left saw Ben Foden and Bruce Reihana combine neatly to send Diggin over on the left flank to the delight of the majority of an enthralled Franklin's Gardens.
It was tough on Worcester, who plundered a smart try after 17 minutes when Myler's kick was charged down and centres Greg King and Alex Grove showed patience to send Benjamin over.
When the Worcester pack produced a tremendous scrum and Horstmann spun away off the back to dive over, it appeared the Warriors might produce a shock victory.
But Saints gathered themselves after Dowson's try, and led by the ball-carrying of new captain Dylan Hartley and prop Soane Tonga'uiha, had enough in their armoury to see them home.
Northampton director of rugby Jim Mallinder:
"It was a nervous performance but it is always good to start with a win, especially at home.
"At half-time I told the players to keep playing. We were playing most of the rugby, had most of the possession but had given away a soft interception try.
"Shane [Geraghty] made quite an impression, he had a good game and when he moved into number 10 was very composed and kicked the vital goals."
Worcester director of rugby Mike Ruddock:
"Walker [when he was sin-binned late on] felt he was OK in the tackle area but referees have to make a call in the heat of the moment.
"The referee is very experienced and we have to support his decision. I felt we could hang on and win ugly but the loss of Walker was crucial as they were able to outflank us for the winning try.
"But I'm very proud of my players. A lot of people are writing us off as no-hopers but we certainly showed a lot of hope today.
"We deserved at least a draw and the players are very down."
Northampton: Ben Foden; Paul Diggin, Jon Clarke, Shane Geraghty, Bruce Reihana; Stephen Myler, Lee Dickson; Soane Tonga'uiha, Dylan Hartley (capt), Santiago Bonorino, Courtney Lawes, Juandre Kruger, Phil Dowson, Neil Best, Roger Wilson
Replacements: Regardt Dreyer for Bonorino (31), James Downey for Myler (52), Scott Gray for Best (61), Ignacio Fernandez Lobbe for Lawes (67).
Not Used: Brett Sharman, Alex Waller, Alan Dickens, Chris Ashton.
Worcester: Chris Latham; Marcel Garvey, Alex Grove, Greg King, Miles Benjamin; Willie Walker, Ryan Powell; Matt Mullan, Aleki Lutui, Olivier Sourgens, Greg Rawlinson, Craig Gillies, Tom Wood, Pat Sanderson (capt), Kai Horstmann
Replacements: Tevita Taumoepeau for Sourgens (12), Graham Kitchener for Gillies (60), Adam Black for Mullan (64).
Not Used: Chris Fortey, James Collins, Jonny Arr, George Crook, Rico Gear.
Sin-Bin: Walker (73).
Ref: Chris White (RFU).