Toulouse and France outside half Frederic Michalak is set to be sidelined for several weeks after sustaining a right ankle injury during his side's 25-12 European Cup rugby defeat of Northampton.
Michalak collapsed after being tackled by Northampton's Andrew Blowers in the 11th minute of the match and limped slowly off the field.
"He felt a strain but not a tear," Toulouse physiotherapist Christophe Foucaud said afterwards.
"We are now going to send him for a scan to find out the exact extent of his injury and to see how long he will be out for. But it looks like being several weeks.
"We need to find out if there is any damage to his fibula," he added.
"That's what concerns us most."
Toulouse, last season's beaten Heineken Cup finalists, went top of pool three after Saturday's win atoned for last week's 23-21 loss to Northampton.
Their next pool match is away to Glasgow in January.