A bullish performance by Exeter tighthead Tomas Francis could trigger a tug-of-war between Stuart Lancaster and Warren Gatland after the 21st 2lb prop helped end Northampton ’ s three-month unbeaten run in the Aviva Premiership . Against a side who pride themselves on the set-piece , Francis dominated his scrummaging contest against Alex Corbisiero and put down a significant marker for his inclusion at the World Cup . The 22-year-old — who qualifies for both England and Wales — is yet to pledge his international allegiance , despite having been called up to Gatland ’ s training camp during the RBS 6 Nations . Dave Ewers ( right ) tackles Samu Manoa of Northampton Saints during the Aviva Premiership match . Chiefs prop Tomas Francis , who qualifies for England and Wales , impressed up against Alex Corbisiero . ‘ Tomas is a young man and will only get better through regular exposure , ’ said Exeter director of rugby Rob Baxter . ‘ He ’ s been to a Welsh training camp , but he ’ s English. ’ With Wales suffering from injury problems in the front row , Francis ( right ) could be fast-tracked through the ranks to face England in the World Cup pool match . But his performance at Sandy Park may tempt Lancaster to make a late move for the youngster , with Chiefs moving back into the play-off positions with three games to play . Christian Day ( right ) and Alex Corbisiero of Northampton drive at the Exeter defence during their defeat . Try-scorer Elliot is tackled by the Chiefs defence as they tried to start a comeback but were n't able to . Some suspected a Saints backlash following their European exit to Clermont Auvergne but a yellow mist descended and the champions paid the price for indiscipline and inaccuracy . With Calum Clark , Stephen Myler and Alex Waller all sin-binned within 15 minutes of each other , Exeter turned the screw and sent Northampton home empty handed . Exeter started sharply with Phil Dollman touching down before Northampton pulled back through James Wilson ’ s try . Mitch Lees ( right ) attempts to drive through Northampton number eight Dickinson at Sandy Park . Lees attempts to break a tackle of the Saints forwards as he helped his side to victory over Northampton . Henry Slade ’ s penalties and the Saints ’ ill-discipline kept Exeter in charge before Francis ’ pressure at the set-piece helped earn a penalty try . ‘ They put our set piece — particularly our scrums — under pressure , ’ said Saints director of rugby Jim Mallinder . Jamie Elliot dived over for a late try , but it was scant consolation for the travel-weary Northampton . Wasps ' Tom Varndell on his way to a try hat-trick . Leigh may miss semi . Leigh Halfpenny could miss Toulon ’ s Champions Cup semi-final against Leinster after suffering a suspected dislocated shoulder during Saturday ’ s Top 14 victory over Grenoble . However , Saracens are confident fly-half Owen Farrell will recover from a knee injury in time for their semi-final against Clermont Auvergne . Winger Tom Varndell scored a hat-trick of tries as Wasps secured a bonus point 40-13 victory at London Welsh . Despite keeping their top-six hopes alive , Wasps director of rugby Dai Young warned : ‘ We need to improve. ’ Sale director of rugby Steve Diamond hit out at referee Greg Macdonald after a surprise 25-23 defeat at London Irish . ‘ For the critical try just before half-time , their player was 15 metres offside , ’ said Diamond .
Exeter moved up to fourth after completing a double over Northampton . Phil Dollman and a penalty try helped the Sandy Park on their way to victory . James Wilson and Jamie Elliot scored for the Saints but to no avail .