Chris Boyd says Saints may have to 'go a bit further into the depths of our roster' for Saturday's big derby date with Leicester Tigers at Twickenham.
Boyd steered his side to a 45-40 victory at Bristol Bears on Saturday, but it may have come at a cost.
Although Saints don't appear to have suffered any serious injuries, the likes of Piers Francis, Courtney Lawes, Dan Biggar and Luther Burrell all took knocks.
And Boyd said: "We're a little bit beaten up.
"Dan Biggar, Courtney Lawes, Piers Francis and Luther Burrell were all pretty sore so we might have to go a bit further into the depths of our roster for the Rob Horne testimonial match.
"We'll just see who comes through."
On Biggar, who was replaced by Harry Mallinder after appearing to tweak his hamstring while taking a 60th-minute conversion, Boyd said: "I talked to him afterwards. He said he was a bit tight at the back end of the week and it was a bit of a niggle.
"Having to take that drop-kick quickly, it just tweaked.
"I don't suspect it's going to be significant."
England lock Lawes was walking gingerly as he left the field with 20 minutes to go.
"He had a little back spasm," Boyd said.
"He's had a pretty big load for us. He's played 80 minutes in the first four games.
"To bring him off and leave Dave Ribbans off, who has been good for us - we were comfortable with that.
"Courtney should be fine."
Burrell did stay on for the full 80 minutes, but Saints would have taken him off had they not had to replace Francis, who sustained concussion early in the game.
"Luther was pretty solid," Boyd said.
"He ran particularly hard with the ball and made some good reads in defence.
"I thought it was a much improved effort from him.
"If we hadn't have lost Piers early on, we probably would have taken Luther off with 15 minutes to go because he was just hanging in there, battling a leg injury.
"We had to leave him out there."