Jim Mallinder insists Saints can't be satisfied with going top of the table.
Instead, the director of rugby urged more improvement from his men after their 30-22 victory against Harlequins at Franklin's Gardens on Saturday afternoon.
Saints secured their third successive bonus-point victory and their fourth win in a row as their transformation since the opening-day defeat to Saracens at Twickenham continued.
Tries from George North, Tom Collins, Mike Haywood and Ahsee Tuala made sure of another maximum haul.
And that was enough to put Saints at the summit of the Aviva Premiership on points difference.
But Mallinder said: "It's a nice place to be but we won't be satisfied with that because it's just a position.
"But we've won four on the bounce, it's another bonus point and it's good.
"We've got lots of things to work on because that's not championship-winning form, but it was winning form, which was good."
Harlequins pounced on a Luther Burrell pass to go ahead during the first half, but Saints always seemed to be the better side at the Gardens.
Despite that, Mallinder knows his men must continue on their upward curve as they prepare for a trip to face Gloucester at Kingsholm next Saturday.
"We went out to a bit of a lead, thought we had a grip on the game, they weren't really in our half and then they got an interception and suddenly they were back in it," Mallinder said.
"We had to work hard to get ahead and we never really got that far ahead. They scored just before half-time (through Jamie Roberts).
"Some of our receiving from kick-off needs to be looked at because every time they kicked to us we seemed to lose the ball and they seemed to score so that's an obvious point where we can improve.
"We talked about them liking a loose, fast game and we just gave them a bit too much today."