The play-maker started for Racing 92 in their Top 14 clash with Toulouse, but was forced off just before the interval after a collision with Lucas Tauzin.
As he went to tackle the Toulose centre, Tauzin’s knee connected with the side of the former Glasgow Warriors fly-half’s face, resulting in Russell needing to leave the pitch for a head injury assessment (HIA).
The 26-year-old didn’t reappear for the second period and was replaced by Ben Volavola after the break.
Russell played just six days before Gregor Townsend’s men take on their French counterparts at the Stade de France, despite Racing and Toulose resting their French internationals.
With the majority of concussions taking up to ten days of recovery time, Russell would be ruled out of Scotland’s third Six Nations game this weekend.
However, there was better news for the Scots on Stuart Hogg. There were fears last week that the full-back could be sidelined until the summer, ruling him out of the remainder of the Six Nations as well as Glasgow’s remaining fixtures and, potentially, the start of the 2019 Rugby World Cup in September.
The player, who is due to join Exeter Chiefs in the summer, was assessed by medical staff from Scotland and Glasgow after suffering a shoulder injury in the early stages of the 13-22 loss to Ireland.
The Sunday Times reported that the player would not require surgery and even if the crunch match at Twickenham was too soon for him, he stood a good chance of being fit for Glasgow’s Champions Cup clash with Saracens on March 30.
However, Hogg stands an outside chance of regaining fitness in time for the Calcutta Cup clash with England in the final round of matches.
Blair Kinghorn will likely assume full-back duties for at least the next two matches against France and Wales, while Adam Hastings or George Horne could replace Russell at fly-half.
Edinburgh head coach Richard Cockerill has already backed Kinghorn to “do a job”, adding: “Fifteen is where we play him and he can fit in there from the start at international level if needed no problems.”
More than 15 players were ruled out ahead of the start of the Six Nations tournament including regular Scotland captain John Barclay, Toulose lock Richie Gray and back-rower David Denton.
Since the start of the 2019 edition, Exeter forward Sam Skinner and Glasgow centre Huw Jones have been sidelined, although there was promising news in the front-row with tighthead prop Zander Fagerson completing 50 minutes in Glasgow’s 38-34 PRO14 win over Cardiff Blues on Saturday night.
Nick Grigg’s performance against the Welsh side could see him get the nod to replace Jones against the French while Fagerson could come into contention for the match in Paris.