Harlequins and England scrum-half Danny Care will be out of action for eight weeks after suffering an ankle injury in training which needs surgery.
The 32-year-old will miss the club's early season cup fixtures and the start of the new Premiership campaign.
"We are disappointed to lose 'DC' for this period," said Quins head of rugby Paul Gustard. "He's a real talisman in our attack."
Meanwhile, hooker Elia Elia (hamstring) is out for six to eight weeks.
The Samoa international, who joined the club in 2016, hopes to return early in the new Premiership season, which Quins begin with a trip to Exeter on 19 October.
Care, who won the most recent of his 84 England caps against Japan last November, will undergo surgery in the next few days. His recovery will then be supervised by the club's medical department.
"Although we won't be able to utilise Danny's talents on the field, we will be able to lean heavily on his experience and character off the field in different capacities to ensure he still has a full role to play in the start of our campaign," said Gustard.
"The club will support 'DC' through his rehabilitation, and I am confident he will return faster than predicted and in excellent shape."