Pedro Neto's double at the Hill Dickinson Stadium ended Everton's unbeaten ‌start to the league season but Chelsea's battling victory was overshadowed by the lengthy injury stoppage in the second ‌half.

Martinez and Branthwaite came together when Everton's Kiernan Dewsbury-Hall ‌whipped a free kick into the box and although the defender was back on his feet after treatment, the Argentina goalkeeper required ‌treatment from paramedics.

The 34-year-old was eventually strapped ⁠to a stretcher and ‌carried off the field before being taken to hospital.

"It was a ​concussion but beyond that I don't know. I have only seen one clip of the incident, ​so we need to wait," Alonso said. "What we know is that he left the stadium conscious and right now ⁠he is in hospital ​doing precautionary tests. We need to wait. Hopefully it won't be too bad but we need to wait."

Martinez's injury forced Alonso to give Mike Penders his Premier League debut, and the 21-year-old keeper helped Chelsea keep their first clean sheet in the league since January.

Penders, a Belgian youth international, may have to step in for the short term due to concussion protocols preventing Martinez from returning to training immediately.

Chelsea host Tottenham Hotspur in the league next Saturday, followed by a League Cup fourth-round game at Liverpool on October 28th and a home Premier League match ‌against Manchester United three days later.

"Mike has personality. He's ​brave and we have full trust with him. He ‌did well," Alonso added.

"He played in the cup games and whenever he's needed, like the other players whenever they are needed they can perform.

"It's all about the squad, that all the players feel important and ⁠can have their moment whenever ⁠they are needed, and ‌that's very positive."