The Brazilian was brought in to provide goalkeeping cover, but the Blaugrana will start the season without their new signing
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.
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.
Barcelona announced on their official website that Neto has been diagnosed with a scaphoid bone fracture and the extent of the injury will be determined on Monday.
Reports in Spain suggest the Brazilian, who featured in Barcelona’s first four pre-season matches, is likely to miss five weeks of action.
While Neto’s time at Barcelona has started in rough fashion, the former Valencia keeper recently described his move to Camp Nou as a dream.
“It’s a dream for any footballer. When you talk about Barcelona, ever player at the highest level wishes to play for a team like this one,” Neto told SPORT.
“It’s very different. It means your hard work has paid off when your club can compete for every trophy available.
“For me, as someone who likes to always win, to compete at the highest level is the best.”
Barcelona begin their La Liga campaign with a trip to Athletic Bilbao on Friday and face Real Betis and Osasuna before the end of the month.
The reigning Spanish champions will also likely be without Lionel Messi for their season opener, with Valverde declaring he’s a major doubt due to a calf strain.
“He’s in the recovery process and I don’t know if he will be ready for the start of La Liga,” Valverde told a news conference after a 4-0 win over Napoli in Michigan on Saturday.
“It’s looking difficult.”
Barcelona have won their last four games of pre-season with their final victory over Napoli seeing Antoine Griezmann net his first goal for the club.