Paris St-Germain striker Neymar was taken off on a stretcher during their win over Marseille, nine days before their Champions League last-16 second-leg tie against Real Madrid.
The £200m striker appeared to twist his ankle while chasing Bouna Sarr.
PSG beat Marseille in Le Classique with ease, as Kylian Mbappe smashed home the opener and Rolando turned Neymar's pass into his own net for the second.
Edinson Cavani swivelled and fired in a third from Neymar's pass.
Paris St-Germain - who are 14 points clear of second-placed Monaco in Ligue 1 - host Real Madrid on Tuesday, 6 March, trailing 3-1 from the first leg.
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Neymar has scored 29 goals in 30 games since his world-record move from Barcelona in the summer.