Leicester hooker Tom Youngs and Gloucester centre Henry Trinder have both been sidelined after suffering shoulder injuries.
Youngs damaged his AC joint after coming on against Bath last weekend, according to the Leicester Mercury.
The England number two will be out for three months, forcing him out of the November Tests. Youngs missed the tour to New Zealand earlier this year for family reasons.
Gloucester meanwhile have confirmed that Trinder, who is uncapped but has featured for the England Saxons, has successfully undergone surgery on the shoulder that he injured during the recent Aviva Premiership victory over Sale Sharks.
The 25-year-old centre, who started Gloucester’s first two Premiership games of the season, was forced to leave the field during the latter stages of the Sale match.
The injury was assessed during the days following that game, before the decision was taken to opt for surgery over the weekend.
The procedure was a success and as Trinder recovers from surgery, he will follow a shoulder rehab programme that will allow him to return to play as soon as possible.