Thomas Castaignede produced a brilliant individual score to settle a pulsating derby game in Saracens' favour.

The Frenchman beat six defenders to claim the 48th-minute try that secured his side's fourth successive Premiership victory since the arrival of former Australia coach Eddie Jones at Vicarage Road.

Glen Jackson added a conversion and three penalties in a win that takes Sarries an important step closer to securing a Heineken Cup place next season.

Wasps had won 12 of the 13 previous meetings between the sides but could not find their way through a superb defensive line with Mark Van Gisbergen's four penalties their only return.

And the defeat has serious implications for the champions' hopes of finishing in the top two and guaranteeing a home semi-final in the end of season play-offs.

They might have to go into those post-season games without veteran scrum-half Matt Dawson, too, after the 33-year-old was forced out of the game with an ankle injury in the first half.

Saracens had only made sure of Premiership survival nine days earlier with a 17-13 win over doomed Leeds, but were able to strengthen their squad with players coming back from injury and England Sevens duty.

Castaignede took over from Dan Scarbrough on the wing and Ben T Russell was on the bench in the two changes to the side that won at Headingley.

Wasps boss Ian McGeechan opted to start with the same half-backs - Dawson and Alex King - who came on to clinch last weekend's 26-10 Powergen Cup final victory over Llanelli Scarlets.

Dawson dominated the opening stages his final meeting with long-term England rival Kyran Bracken, directing operations.

His dart down the blindside set up the position for Van Gisbergen's fifth-minute penalty and the full-back doubled the lead after 12 minutes when Saracens were slow to release the ball.

Jackson opened the home side's account at the end of the first quarter with a penalty after a series of driving mauls in a good spell that also saw Tevita Vaikona and Ben Johnston start to open the game up.

Wasps responded with their most fluent attack so far when Stuart Abbott punched his way through the middle and was prevented from recycling the ball with Van Gisbergen adding a further three points.

Dawson's involvement ended soon after his right ankle was damaged in a tackle from Taine Randell that arrived a fraction of a second after he had released the ball.

Eoin Reddan took over before Saracens produced their best spell of the game, Castaignede's break launching a series of attacks that saw Kris Chesney denied by Dallaglio's saving tackle in the corner before Wasps were caught offside and Jackson's second penalty made it 9-6 to the visitors at the break.

Castaignede then lit up the match at the start of the second-half.

The Frenchman was hopelessly outnumbered when the ball was recycled to him, only to dance his way past half-a-dozen tacklers - Wasps would argue their defenders were hindered by a blocking runner - to score under the posts with Jackson converting.

The score came against the run of play and Wasps immediately set up camp in the home side's territory, but they struggled to turn their supremacy into points with Van Gisbergen's fourth penalty on the hour their only reward.

Saracens bottled up the three-time champions after that and the only positive on a grim afternoon for Wasps was news from elsewhere that league leaders Sale had failed to overcome Newcastle.