Barcelona forward Neymar is likely to miss the Spanish club's opening La Liga game of the season against Elche on Sunday after injuring an ankle.
The 22-year-old Brazil international scored twice during a 6-0 pre-season defeat of Mexican side Leon on Monday.
But less than a week after being given the all-clear from the fractured vertebra he suffered at the World Cup, Neymar was injured in training.
"Tests have shown a grade one sprain," said a Barcelona statement.
"His return to training will depend on how the injury treatment evolves."
Barcelona begin the season under new coach Luis Enrique having overhauled their squad following their first season without a major trophy in six years.
They paid a reported £75m to sign Liverpool striker Luis Suarez, although Barcelona subsequently said the figure was nearer £65m, while defender Thomas Vermaelen was bought from Arsenal for £15m.