Injury blows for England as Saints lose their top spot

Northampton 6 Saracens 16: Hartley and Lawes both forced off in first half as Ashton makes a boisterous winning comeback

Fresh from a fortnight in Europe, and attention turning to matters domestic and international, Saracens extended their impressive record this season to seven wins and a draw in eight matches, while Northampton lost two of their England forwards – Dylan Hartley and Courtney Lawes – to injury in the first half.

Hartley, the 42-times capped hooker and a prospective national captain in the unlikely event England turn away from Harlequins' Chris Robshaw for next month's Tests at Twickenham, limped off with a knee problem at half-time. He joined Lawes, who received treatment to his left knee very early on after playing a part in halting an attack by Saracens' Brad Barritt, and failed to make it through the opening half hour.

Lawes had been expected to make a return to England's second row in the game against Fiji at Twickenham on Saturday week, having missed the summer tour to South Africa on which Hartley was skipper for the final Test.

Both men were said to be walking without crutches in the changing room immediately afterwards, but Northampton's director of rugby, Jim Mallinder, was unable to make a detailed prognosis in either case. Of course, Mallinder and the majority in the crowd were more concerned with the Saints slipping to a third defeat in four matches and a seventh in their last eight meetings with Saracens, and losing their place at the top of the Aviva Premiership .

But the removal of two of the 11 England squad members on view was a wider worry with the national team gathering today at St George's Park, Burton on Trent, for a four-day training camp; the 23 to face Fiji will be kept back from next weekend's Premiership matches.

Chris Ashton, the England wing returning to the scene of dozens of tries that he scored here in Northampton colours before his summer transfer to Sarries, made the tackle on Hartley that led to the latter's injury. Ashton also had a run-in with his opposite number, Vasily Artemyev, that raised the temperature – though only metaphorically, in the biting north wind and hail. Saints' Russian cutely blocked off a run by Saracens' winger and took an angry push in the back in response. In the next move Artemyev was about to boot the ball down the wing when Ashton barged him into touch with a tackle that was, at best, clumsy. Ashton took a talking-to but no card from the referee, Andrew Small, who awarded a penalty. "They were both moving fast and it looked to us like Chris was bringing his shoulder round," said Paul Gustard, Saracens' assistant coach. Mallinder said: "It wasn't a red card but it wasn't the best tackle I've seen." The authorities have promised to clamp down on such no-arm challenges and, if a few hollering Saints supporters nearby had anything to do with it, the citing officer would take an interest. The visitors' rotation policy brought Owen Farrell into the starting line-up, with Charlie Hodgson on the bench. Farrell has had on and off days with the boot this season, after a stuttering start with shoulder and groin injuries, and he is behind Leicester's Toby Flood in the national pecking order.

But Farrell thumped a penalty over from two metres inside his own half after seven minutes – Steve Myler replied five minutes later before being substituted at the same time as Lawes with a sore hamstring – and Farrell converted a counter-attacking try by Saracens with 25 minutes gone. George Pisi made up ground on Northampton's right wing but lost the ball and Neil de Kock launched Sarries in response. A weaving run by Schalk Brits took them over halfway, Joel Tomkins took it on and the centre's inside pass sent the full-back Alex Goode – another England candidate – jogging to the posts. Saints worked mightily to wrest an advantage out of Saracens' scrum, and the home maul was a weapon too. But England's new recruit, Mako Vunipola, held up well as Sarries' loosehead and made one crucial tackle on Artemyev in the final quarter.

Throughout the second half – which began with Ryan Lamb and Farrell swapping penalties for Saracens to lead 13-6 – Northampton's backs were often static or running diagonally. Ashton might have scored with a neater touch with the foot as he chased Tomkins's hack. Farrell's penalty in the 67th minute after Northampton's forwards killed the ball gave the fly-half four successes out of four. Lamb tried a little chip on his 22 to ignite an attack, Artemyev perhaps thought for a second he had finally got away, but Hodgson, on for his younger confrere at No 10, chased back magnificently.

"When things get tough we've got a friend to the right, and a friend to the left, and they will fight for each other," said Gustard. Northampton's sponsors made Saracens' Barritt man of the match, and Ashton was seen to stay behind socialising with his old club-mates for a couple of hours. So that was nice.

Northampton S Myler (T May, 27); K Pisi, G Pisi, D Waldouck (L Burrell, 69), A Artemyev; R Lamb, L Dickson (M Roberts, 69); S Tonga'uiha (A Waller, 62), D Hartley (M Haywood 40), P Doran Jones (B Mujati, 51), C Lawes (S Manoa, 27), M Sorenson, P Dowson, GJ van Velze (R Oakley, 74), T Wood.

Saracens A Goode; C Ashton, J Tomkins, B Barritt, D Strettle; O Farrell (C Hodgson, 69), N de Kock; M Vunipola, S Brits (J Smit, 61), M Stevens (C Nieto, 55), S Borthwick (capt), A Hargreaves (M Botha, 24-31, 60), K Brown, J Wray (E Joubert, 51), W Fraser.

Referee Andrew Small .

Attendance 13,475.

Northampton

Pens: Myler, Lamb

Saracens

Tries: Goode

Con: Farrell

Pens: Farrell 3