The Catalan club had already confirmed that young midfielder Arthur was set to move to the Italian champions for a fee that could rise to €82m.
And his direct replacement will come from the same club, with the 30-year-old signing a four-year deal at Camp Nou.
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"FC Barcelona and Juventus have reached an agreement for the transfer of player Miralem Pjanic," a club statement reads.
"The cost of the operation will be 60 million euros plus 5m in variables.
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"The player will sign a contract with the club for the next four seasons, until the end of the 2023/24 season, with a buy out clause of 400 million euros.
"The player will remain with Juventus until the 2019/20 season is over."
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The Bosnia and Herzegovina international moved to Juve four years ago from Roma. He had previously represented Olympique Lyonnais and Metz, where he began his career.
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