London - England coach Eddie Jones' preparations for the November Tests suffered another blow on Friday with lock George Kruis sidelined after undergoing ankle surgery.
The 26-year-old Saracens star - an integral part of Jones' Six Nations Grand Slam-winning side this year - should only be out of action for a few weeks, according to his club.
"After consultation with George and England, we are all in agreement that it's in the best interest of the player to undergo this minor procedure now with the majority of the season still ahead of us," said Saracens director of rugby Mark McCall.
"George is on the road to recovery and we look forward to his return to action sooner rather than later."
Jones, who in a short space of time revived an England side demoralised after bowing out of the 2015 World Cup as hosts at the first hurdle, will definitely be without veteran back-row forward James Haskell, injury-prone centre Manu Tuilagi, outstanding wing Anthony Watson and Wasps flanker Sam Jones.
The latter pair's injuries - Watson suffered a broken jaw and Jones a broken leg - brought the England coach a load of criticism as they occurred at a training session organised earlier this month.
Jones broke his leg in a judo session - tussling with Maro Itoje - in a bid to improve their tackling.
McCall labelled the timing of the England camp in the south coast town of Brighton as "madness" and "flabbergasting".
England will go into the November internationals - they play Argentina, Australia, Fiji and South Africa - having won all nine Tests played under Jones.