George North has suffered another injury blow after being forced off at Twickenham last Saturday.
The Wales star will now be out for the next four weeks after sustaining another knee problem during the 50-21 defeat to Harlequins.
North was making his first appearance since the defeat to Saracens in October, during which he sprained his posterior cruciate ligament.
But after being introduced off the bench in place of Ahsee Tuala, who hobbled off on 25 minutes, North took a knock to the same knee he injured against Saracens and was limping.
He eventually left the field 15 minutes from the end of the match, being replaced by scrum-half Cobus Reinach.
And North, who is leaving Saints to return to Wales at the end of the season, will now be forced to spend more time on the sidelines as he recovers.
Saints coaching consultant Alan Gaffney said: “While it’s disappointing that George will be missing ahead of Saturday’s game (at home to Gloucester), this injury means an opportunity for another player in the squad to step up to the plate.
"I’m sure George will be diligent in his rehab and we all wish him a swift recovery.”