England captain Lawrence Dallaglio faces an anxious wait after limping off with an injured right knee at Franklin's Gardens.

The Wasps back row star is due to lead England in next Saturday's World Cup qualifier against Holland but twisted his knee after being trapped at the bottom of a ruck.

Chief executive Nigel Melville later described the problem as "nothing serious" and Dallaglio will join up with the rest of the England squad as planned.

He said: "At this stage, we are not talking about x-rays or scans, and the knee is not swollen at the moment. The extent of any swelling over the next 24 hours will determine what happens after that."

The win puts Northampton level on points with second-placed Bath with a game in hand, and only two behind leaders Leicester.

They led 17-0 inside 20 minutes following a blistering opening, but in the end it was Paul Grayson's immaculate goal-kicking which saw Saints home.

It was England fly-half Grayson's first Premiership start since mid-October, but he displayed ice-cool nerves to keep Northampton in front as Kenny Logan led Wasps' revival.

Scotland wing Logan also amassed 16 points, including a 75th-minute corner try, yet Grayson showed his big-match experience when it really mattered.

A lively match saw one player from each side sin-binned, Northampton flanker Don Mackinnon for punching and Wasps' England prop Will Green when he tackled Matt Dawson after not retreating 10 metres at a penalty.

Northampton started in breathtaking fashion, Grayson kicking a penalty then Mackinnon sprinting 20 metres to the Wasps try line when Pat Lam sent him clear.

Ten minutes later the irrepressible Lam rifled out a defence-splitting pass which full-back Nick Beal pouched on to touch down.

Grayson's touchline conversion put Northampton well on their way, but Wasps' forwards dug deep and flanker Paul Volley was driven over for the timely try which Logan improved.

Logan then booted three penalties in quick succession and although Grayson managed one in reply, Northampton's lead had been whittled down to four points entering the closing quarter.

Another Grayson strike gave Saints some breathing space but Wasps centre Rob Henderson then broke through from deep and sent Logan sprinting over.

He could not add a difficult conversion and Grayson made it safe with a fourth penalty three minutes from time.

"Paul looked as though he wanted to play today. It was by far his best game of the season," said home coach Ian McGeechan.

Northampton: Beal, Moir, Dantiacq, Allen, Sleightholme, Grayson, Dawson, Pagel, Johnson, Hynes, Metcalfe, Rodber, MacKinnon, Pountney, Lam Replacements: Malone, Hepher, Blyth, Walter, Volland, Phillips, Seely.

Wasps: Ufton, Roiser, Scrase, Henderson, Logan, Lewsey, Friday, Molloy, Leota, Green, Weedon, Shaw, Dallaglio, Volley, Worsley Replacements: Gomarsall, Greenstock, Rollitt, Macer, Rossigneux, Reed, Black.