Barcelona goalkeeper Neto is facing a spell on the sidelines after fracturing a bone in his left wrist.
The 30-year-old arrived at Camp Nou from Valencia during the off-season in a deal worth an initial €26 million (£23m/$30m.
With Jasper Cillessen moving the opposite way, Neto was brought in to provide competition for Marc-Andre ter Stegen.
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But Ernesto Valverde now faces being without his back-up keeper for the opening stages of the season as he picked up an injury in the final training session ahead of Saturday's friendly against Napoli.