The Amlin Challenge Cup champions went down by 23-15 as the Saints moved three points clear of Castres Olympique at the top of Pool 1.
Northampton Saints director of rugby Jim Mallinder believes next weekend’s return clash with Cardiff Blues will give him a true indication of how much his side has progressed this season.
“Next week will be a real test of where we are as a team. To go down to Cardiff and get a win would be a real sign of our growing maturity,” said Mallinder.
“It wasn’t our very best performance, but it was a hard fought win. We didn’t dominate at the set piece, although we got quite a lot of return from the scrum.
“But they defended our drive very well and we have to look at our first half performance a little bit. We were down at half-time and we then got 16 unanswered points.
“The Blues are a good side who like to move the ball. We will need to look at the breakdown and we must keep 15 men on the field.”
French referee Romain Poite sent five players to the sin-bin during the game – James Downey, Courtney Lawes and Dylan Hartley for the home side and Tau Filise and Gareth Williams for the Blues – and dished out a stream of penalties at the scrum and breakdown.
In the end, though, it was the power of the Saints’ pack that caused the Blues so much trouble their line-out coughed up six throws and they conceded a number of penalties at the scrum.
Despite dominating possession in the opening 10 minutes, and taking the lead with a Dan parks penalty, the Blues soon felt the full force of Dylan Hartley’s home eight.
Five scrums, and three penalties, in the visitors’ 22 ended with scrum half Ryan Powell sending left wing Paul Diggin over in the corner for the game’s first try.
Steve Myler added the touchline conversion, but the Blues got their act together and gave the sell-out crowd of 13,499 a few anxious moments as Parks landed three successive penalty attempts to put his side into a 12-7 lead.
The last kick came after Saints centre Downey was sent to the sin-bin for a dangerous tackle, but it was 14-a-side a minute later when Blues prop Filise used his hands at the ruck.
That gave Myler the chance to cut the gap to two points at the break and two minutes after the re-start the home outside half was adding the extra points to a second Saints try from England wing Chris Ashton.
That started when Blues skipper Paul Tito lost control of the re-start and the Saints’ jumbo pack immediately took advantage. They worked their way up to the line and then quick hands released Ashton on the right.
That made it 10 points in three minutes around the half-time interval and Myler dished out further punishment 10 minutes later when the Blues conceded another penalty at a ruck on their 10 metre line and added another after 66 minutes to extend the gap to 11 points.
Parks added a fifth penalty after England lock Lawes had been sent to the bin for failing to roll away at a ruck in front of his posts and then the game ended in controversy with opposing hookers Hartley and Gareth Williams being yellow carded for fighting.
