London - Scotland flyhalf Finn Russell has been ruled out of Saturday's Six Nations match away to France with a head injury, Scottish Rugby announced Tuesday.
The influential playmaker was substituted before half-time for Paris-based club side Racing 92 in Sunday's loss to Toulouse and failed the initial head injury assessment.
Russell had six days in which to satisfy protocols for returning from a head injury and when he joined up with the Scotland camp symptom free on Monday, team management felt there was still an outside chance he could face France.
But the Scottish Rugby Union statement put paid to those hopes on Tuesday, with a statement saying: "The 26-year-old playmaker has not satisfied the requirements of today's component of the graduated return to play protocol - two days on from sustaining the injury in Racing 92's Top 14 clash with Toulouse - meaning there is insufficient time for him to be considered for this weekend's action.
"He will now return to the care of his club's medical team."
Scotland, already hard hit by injuries before the Six Nations, will now be without six of the players who started in their opening win over Italy.
Full-back Stuart Hogg, who suffered a shoulder injury in a 22-13 defeat by Ireland at Murrayfield on February 10, centre Huw Jones and Russell are all missing from behind the scrum.
Meanwhile forwards Ryan Wilson, Sam Skinner and WP Nel have been sidelined from Scotland's pack.
Scotland coach Gregor Townsend, whose side are third in this season's Championship standings, is due to name his team to play France on Thursday.
Townsend added Worcester flyhalf Duncan Weir as cover for Russell on Monday, while Adam Hastings - the son of Scotland great Gavin Hastings - and Glasgow team-mate Peter Horne can play at stand-off as well.
Scottish players based at clubs abroad - like Russell - can still feature for the national team, unlike the situation in England.
Had Russell been at Glasgow or Edinburgh, however, it was likely he would have been rested for last weekend's round of Pro14 matches as was the case with several of his Scotland team-mates.
His injury highlights the problems countries with a relatively small playing base such as Scotland face when leading players opt for more lucrative club deals overseas.