New signing Claudio Bravo made a costly error on his Barcelona debut as his team suffered a 1-0 friendly defeat against Italian side Napoli.
Barcelona, missing their first-choice attacking trio of Lionel Messi, Neymar and Luis Suarez, failed to turn their first-half superiority into goals.
Swansea loanee Michu came on for Napoli as they improved in the second half.
And Rafa Benitez's team claimed victory when goalkeeper Bravo fumbled Blerim Dzemaili's long shot after 80 minutes.
Napoli: Rafael, Maggio (Mesto 46), Albiol (Luperto 85), Koulibaly, Britos (Ghoulam 46), Gargano (Zuniga 72), Jorginho (Mertens 61), Callejon (Dzemaili 72), Hamsik (Vargas 72), Insigne (Inler 61), Zapata (Michu 46).
Barcelona: Bravo, Montoya, Pique (Edgar 60), Bartra (Bagnack 75), Alba (Grimaldo 60), Rakitic (Halilovic 60), Busquets (Samper 60), Iniesta (Sergi Roberto 60), El Haddadi (Ramirez 60), Pedro (Deulofeu 75), Rafinha (Traore 75).