The 31-year-old was out for six months after suffering a cruciate ligament injury in April 2016 and started in the season-opening win over Cagliari but the club said he would undergo treatment and strengthening exercises on the same joint.
Marchisio, who has been capped 55 times, will almost certainly miss Serie A matches against Genoa and Chievo, and could be absent for games against Sassuolo, Fiorentina and Torino.
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He will also be unavailable for the club's opening Champions League fixture at Barcelona on Sept. 12 and Italy's World Cup qualifiers against Spain and Israel.
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