Saints confirm Biggar has suffered knee injury
Biggar was forced off during the second half at Wasps last weekend, having taken several blows.
He appeared to suffer a back problem during the first half, having provided a magical try assist for Alex Coles just before the break.
But he was able to re-emerge for the second period, only to suffer the knee injury, meaning he had to limp off.
But James Grayson could also be an option in the weeks ahead, having impressed hugely during his 27 minutes on the field in the Premiership Rugby Cup win against Harlequins on Tuesday night.
Fin Smith could also soon come into contention, with the 20-year-old having joined Saints with immediate effect from Worcester Warriors earlier this week.
But losing Biggar will undoubtedly be a blow for Saints in what will be his final season at the club.
He is due to head off for international duty with Wales, who start their autumn fixtures with a game against New Zealand in Cardiff on November 5.
Whether Biggar is fit to face the All Blacks now remains to be seen, while he looks unlikely to feature for Saints this month.
The black, green and gold host Newcastle Falcons on Saturday before travelling to Bath and hosting Bristol Bears before the month is out.
"The 32-year-old fly-half was withdrawn in the 42nd minute and the Club’s medical staff have since consulted a specialist regarding the injury.
"Biggar will continue to be assessed by Saints’ medical department over the coming weeks and his condition reviewed by a specialist ahead of the autumn internationals."