Chelsea captain Cesar Azpilicueta was stretchered off the pitch after being knocked unconscious following a kick to the head in worrying scenes at Stamford Bridge.
Southampton’s Sekou Mara collided with Azpilicueta when attempting an overhead kick in the 74th minute.
The match was immediately stopped and medics ran onto the pitch, with a stretcher soon following.
Chelsea's players looked shaken during the nine-minute stoppage, in which Azpilicueta was given oxygen.
The 34-year-old was eventually considered safe to move, placed on a stretcher and then applauded off the field by all four corners of the stadium, having received after treatment from both the home and away medical teams.
In encouraging scenes, the defender was aware enough to respond to the applause by applauding back as he was taken to an ambulance by the on-call medics.
Manager Graham Potter said after the game: “He is in hospital, he is in the best place for him.”
He added: “He is conscious and speaking to his wife.”
Chelsea lost the game 1-0 thanks to a James Ward-Prowse free kick in the first half, piling further pressure on manager Graham Potter.