Joao Cancelo is set for an undetermined spell on the sidelines just eight days after signing for Inter after suffering knee ligament damage on international duty with Portugal.
Cancelo swapped Valencia for San Siro last week, moving on a season-long loan deal, with Inter holding the option to make the move permanent.
The 23-year-old was a 84th minute substitute in Saturday's 3-1 Serie A victory over Roma but that could be his sole Inter appearance for some time.
While training with Fernando Santos' European champions ahead of their World Cup qualifiers with Faroe Islands and Hungary the full-back tore ligaments in his knee and faces time out recovering from the injury.
"Joao Cancelo underwent medical tests this afternoon in Rozzano after picking up an injury while training with Portugal," an Inter statement read.
"The tests revealed that he has suffered a tear to the medial collateral ligament in his right knee.
"Cancelo's condition will be evaluated week to week."