Saints are unbeaten at home in the tournament since 2007 when Biarritz beat them 17-8.
But the Scarlets are the only Welsh club to have won a Heineken Cup tie at Franklin's Gardens, winning narrowly eight years ago, and they will arrive in the east midlands fresh from a solid Pool One victory over dangerous French side Castres.
Northampton, meanwhile, are on the rebound following a demoralising injury-time loss to Munster in Limerick, suggesting tonight's clash under the Gardens floodlights will prove a gripping affair.
"The effort, endeavour and commitment from all our players last weekend was evident," said head coach Davies, who has handed Rhys Priestland the number 10 shirt ahead of his Wales World Cup colleague Stephen Jones.
"We will have to bring real belief, the ability to adapt our game and be sharp because it is going to be a big challenge.
"We have got some momentum now over the past six games, and the players have been playing for the jersey.
"They will need to show real intensity in their performances and put everything into the battles they face.
"We have to be very respectful of the quality that Northampton bring to the game. The set-piece will be key and the boys know that.
"We will have to react cleverly on the pitch as well and adapt to the situations in front of us. The boys have been on the edge this week, but there is a lot of focus, too."
All four Pool Two contenders are in action tonight, with Cardiff Blues hosting London Irish and Edinburgh - the Exiles' surprise Madejski Stadium conquerors last Saturday - meeting Racing Metro at Murrayfield.
The Blues make two enforced changes from the side that accounted for Racing in Paris a week ago. Injuries sideline centre Jamie Roberts and lock James Down, with Dafydd Hewitt and Paul Tito their respective deputies.
Harlequins, victorious in all 11 of their games so far this term, put that unbeaten record on the line against Pool Six rivals Gloucester at Kingsholm tomorrow.
"Winning breeds confidence," Quins rugby director Conor O'Shea said.
"Maybe when you are in the midst of a tough game you find the mental strength to come out on top because the belief is there.
"We were tested big time against Connacht last week, but we had the fortitude to come through. I am delighted we showed that sort of mental strength.
"It's easy to be offloading away and pirouetting down the pitch, but sometimes you have to roll up your sleeves and come up with the goods, and we did that against a tough Connacht team."
Elsewhere tomorrow, early Pool Four pacesetters Leicester and Ulster meet at Welford Road, with Saracens heading to Biarritz in Pool Five, Connacht hosting Toulouse, Munster visiting Castres and Ospreys tackling Treviso in Italy.
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