Itoje left the field during his club's loss to Harlequins on Sunday in the English Premiership after picking up the injury following a collision with England team mate Mike Brown.
"Scans have confirmed that Saracens forward Maro Itoje fractured his jaw in Sunday’s round 10 Aviva Premiership clash against Harlequins,” Saracens said in a statement on Tuesday.
"Itoje will now see a second specialist later this week to confirm his return to play schedule."
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Similar injuries have ruled players out for about two months and England coach Eddie Jones faces a nervous wait with his team's opening Six Nations match against Italy on Feb. 4.
Itoje played every game in England's victorious 2017 Six Nations campaign and three tests for the British and Irish Lions as they drew with New Zealand. He was nominated for the World Rugby Player of the Year award.
(Reporting by Jack Tarrant, editing by Ed Osmond)
