Chelsea goalkeeper Emi Martinez underwent successful surgery after suffering a concussion and a jaw injury in a collision with Everton's Jarrad Branthwaite during a 2-0 Premier League victory.
The 34-year-old Argentine player was strapped to a stretcher, carried off the field, and taken to hospital following the lengthy second-half injury stoppage.
Manager Xabi Alonso handed 21-year-old Belgian youth international Mike Penders his Premier League debut to step in while Martinez recovers.