Saracens forward pair Hayden Smith and Mako Vunipola have undergone surgery and will be out for a number of weeks.
Prop Vunipola, 20, had surgery on a broken foot on Monday and is expected to be sidelined for three months.
Smith, 26, received treatment on a broken hand and will return to the side in six weeks.
summer signing from Bristol
, and 18-time capped USA international Smith have made six appearances each this season.
The Premiership champions are already without scrum-half duo
Neil de Kock
, who have long-term injuries.