Neymar will miss Barcelona's Club World Cup semi-final meeting with either Mexican side Club America or Chinese club Guangzhou Evergrande on 17 December due to a groin strain, according to his father.
The Brazilian forward picked up the injury while training before Barcelona's final Champions League group match against Bayer Leverkusen in Germany.
Neymar Sr said the problem was not serious and that his son would likely recover in time for the final on 20 December, should the Catalans progress to the showpiece event.
"It's an injury like any other grade two injury. It will keep Neymar out of action for at least one week," Neymar Sr was quoted as saying by Catalan daily Sport.
"I believe he will be fine for the [Club World Cup] final, the semi-final [I'm not so sure]."
Barca boss Luis Enrique bemoaned Neymar's injury after his team played out a 1-1 draw with Leverkusen on 9 December.
Neymar is the top scorer in La Liga this season with 14 goals and was named the player of month in November by the Spanish Football League (LFP).
"Of course, it's the bad news from this fixture. It's an unpleasant situation and we have to wait to see what the team doctor says," Enrique was reported as saying by AFP.
"We don't know how bad the injury is and we have to hope he recovers quickly in the next few days.
"It's always unpleasant to lose a player through an injury, possibly long term, and we have to hope it's not as bad as feared."
Neymar will also miss Barcelona's La Liga encounter with Deportivo La Coruna on 12 December.
The Fifa Club World Cup gets underway on 10 December, with New Zealand's Auckland City taking on Japanese side Sanfrecce Hiroshima in Yokohama for a place in the quarter-finals.
Barcelona are looking to win the tournament for the third time after previous triumphs in 2009 and 2011.