London - England and Saracens lock Maro Itoje suffered a broken jaw in a weekend Premiership clash, his club announced on Tuesday, meaning he faces a race against time to be fit for the Six Nations.
The British and Irish Lions player was injured in a collision with Mike Brown as Saracens, third in the Premiership, lost 20-19 to fierce rivals Harlequins in Sunday's match at The Stoop.
Saracens have confirmed Itoje's injury is a fractured jaw and the 23-year-old will now undergo further testing to determine his recovery period.
England launch their Six Nations title defence against Italy in Rome on February 4, giving Itoje two months to be fit to contest selection for Eddie Jones' side.
"Scans have confirmed that Saracens forward Maro Itoje fractured his jaw in Sunday's round 10 Aviva Premiership clash against Harlequins," said a Saracens statement.
"The 23-year-old England forward left the field in the 48th minute of Saracens' 20-19 defeat at the Twickenham Stoop and was taken to hospital where scans confirmed the fracture.
"Itoje will now see a second specialist later this week to confirm his return to play schedule."
The second row will miss Saracens' upcoming European Champions Cup clashes, with the double reigning champions next facing French side Clermont in back-to-back fixtures.
Itoje was nominated for World Rugby's world player of the year for 2017 after a stunning calendar year that comprised England's Six Nations win, Saracens' second European triumph and the Lions' drawn series with world champions New Zealand.