Luther Burrell was taken to hospital after being knocked unconscious during Saints’ defeat at Saracens on Saturday.
The centre bravely flew into a tackle during the second half but collided awkwardly with the hip of Brad Barritt.
He managed to walk from the field, but received oxygen and travelled from the ground in an ambulance.
After the game, Saints boss Jim Mallinder said: “Luther took a blow to the head.
“He was up and chatting in the changing room.”
Teimana Harrison was also forced off during the second half in the 27-12 loss.
And Mallinder said: “Teimana hurt his shoulder. I think it’s an AC joint so hopefully it’s not too bad.”
Dylan Hartley had missed the game due to a back problem.
And Mallinder said: “Dylan came off with a sore back last week and we’re hoping he’ll be returning next weekend.”