PSG play bitter rivals Marseille in Ligue 1 on Sunday at the Parc des Princes.
"Today he was ill," Emery said. "I hope Neymar will be well enough to train tomorrow and will be ready for Sunday, but we will wait."
The Brazilian was sent off when the clubs drew 2-2 in Marseille in October.
Neymar scored last Saturday as PSG bounced back from their 3-1 defeat to Real Madrid in the first leg of their Champions League last 16 tie by thrashing Strasbourg 5-2.
They have a 12-point lead at the top of Ligue 1 as they seek to regain the title from Monaco.