Neymar fractured a bone in his back following a challenge from Colombia defender Juan Zuniga in Brazil's World Cup quarter-final and was ruled out for the rest of the tournament.
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"I am recovering bit by bit from the injury and I will arrive in Barcelona at 100 per cent," Neymar, who is due back at Barca on August 5, told reporters at a promotional event in Japan.
"I want to have a good season and I would like to help my team mates get good results," he added.
Barca play Mexican side Leon in the friendly at the Nou Camp on August 18, with the winners awarded a trophy named for the Catalan club's founder Joan Gamper. They begin their La Liga campaign at home to Elche the following weekend.
Barca ended last season without major silverware for the first time in six years and coach Gerardo Martino was sacked and replaced by former Spain and Barca midfielder Luis Enrique.
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