Jim Mallinder says Saints need to improve 'in every aspect' of the game after their sobering 30-15 defeat at Sixways on Saturday afternoon.
Mallinder's men conceded four tries as they were beaten by a Worcester Warriors side who had lost all of their previous seven Aviva Premiership matches this season.
It was a third successive loss for Saints, who face a tough league trip to Sale Sharks next Saturday.
And Mallinder said: "We need to do better in every aspect.
"We need to improve our set piece, we need quality ball from lineout and scrum, and what we do with that we've got to be better.
"We need to get the ball back when we kick it, when we run we've got to be more direct, get over the gain line, look after it.
"Their third try came from us just losing the ball from a scrum and us missing a tackle and them scoring from 60 yards out.
"Those things are not good enough and we need to improve those in training from Monday.
"We need to put it right next week up at Sale."
Saints had gone ahead through a Stephen Myler penalty, but they were porous in defence once again as they conceded a try bonus point for the fifth game in six.
Second-half scores from Ben Foden and Jamie Gibson were scant consolation, while Worcester were jubilant as Bryce Heem's hat-trick helped them secured five precious points.
"They came out and they were playing for their lives," Mallinder said.
"They played with real pride, passion and physicality and it was a really disappointing afternoon for us.
"We conceded far too many penalties in the first half - nine to their two - which allowed them to get good field position and when we went down to 14 men, they scored.
"It wasn't helped when we lost Luther (Burrell) early on to a head knock, but we need to be better than that, in all areas.
"We did have our chances, scored a couple of tries and could have had a couple more, but we conceded too many tries."