The 31-year-old flanker fractured his elbow during Toulon’s Top14 defeat to Toulouse on Saturday and is set to be sidelined for up to three months.
“Against Toulouse on Saturday flanker Juan Martin Fernandez Lobbe suffered a fracture of the right elbow,” read a Toulon statement.
“He will consult a Marseille professor for surgery. It is estimated he will be unavailable for two to three months.”
Argentina also face England, Italy and Ireland during their European tour.
Meanwhile former Wales head coach Sir Graham Henry has left his role as technical advisor to Los Pumas.
The World Cup winning-coach has stepped down to focus on a similar role with Super Rugby side the Blues.
He is just the latest departure from the Pumas’ coaching staff after Santiago Phelan quit his role in charge. Phelan had been at the helm for six years but will be replaced by Argentina B coach Daniel Hourcade.
