Barcelona refused Thursday to say when Neymar will return to action after confirming that he suffered a groin muscle tear in training this week.
The injury has made the Brazilian goalscorer a doubt for the start of Barcelona's World Club Cup campaign in Japan next week.
"Tests conducted this morning by FC Barcelona medical staff confirmed that Neymar Jr has a small tear in the adductor muscle of his left leg," the club said.
"The evolution of the tear will determine his availability for the next matches," added the statement without giving details.
Neymar pulled up in training on Tuesday and missed Wednesday's 1-1 draw with Bayer Leverkusen in Barcelona's final Champions League group game.
Barcelona travel to Japan for the World Club Cup after playing Deportivo La Coruna this weekend. Their first game is in the semi-final on Thursday.
Catalan daily Mundo Deportivo said Barcelona hope Neymar will be fit again for the final in Yokohama on December 20.
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