Paris Saint-Germain will be without captain Thiago Silva for "several weeks" after scans confirmed the defender has a hamstring injury.
The 29-year-old was forced off 13 minutes into Monday's friendly with Napoli after attempting to back heel a pass inside his own penalty area, bringing an end to his first PSG appearance alongside new signing David Luiz.
Fears of serious injury were raised when, having been replaced by Marquinhos, the Brazil international was seen hobbling to the dressing room with heavy strapping on his right leg.
After undergoing tests to assess the extent of his injury, the Ligue 1 champions confirmed he is set for a spell on the sidelines.
A statement read: "The examinations carried out on Thiago Silva yesterday (ultrasound and MRI) confirmed a muscle injury to the right hamstring.
"He will be sidelined for several weeks."
Coach Laurent Blanc will hope his squad are able to cope with the loss of their captain in a similar way to last season - they won seven of the eight games Silva missed due to another hamstring problem.
PSG return to league action on Saturday when they welcome Bastia to the Parc des Princes.