Martinez collided with Jarrad Branthwaite as the pair challenged for a cross and after more than eight minutes of treatment the Argentina international was carried off on a stretcher to a waiting ambulance.

“What we know is he left the stadium conscious and right now he is in the hospital doing precautionary tests,” said Alonso.

“It was concussion but more than that I saw only one clip. Hopefully it won’t be too bad but we need to wait.”

Pedro Neto scored at the beginning and end of the second half for his first Premier League double which also helped secure Chelsea’s first top-flight clean sheet since January.

“Really pleased with the performance. With the win, the clean sheet – many positives,” he added.

“We knew it would be a hard challenge to win in this stadium and we got many things right playing professional and very solid. It’s good to have a win in this way.”

Everton boss David Moyes felt his side were on the wrong end of some debatable refereeing decisions, notably Harrison Armstrong’s first-half challenge on Josh Acheampong for which he was booked and also Morgan Rogers’ tackle on James Garner, which referee Paul Tierney and VAR decided did not warrant a second caution.

“We have got referees who we want to be the best in Europe because they let things go but I thought it looked a half-decent tackle (by Armstrong),” he said.

“Someone might tell me different. I wasn’t sure it was the right decision. I was disappointed with the decision at the time.

“I’ve had a wee look at the Morgan Rogers tackle on Jimmy which some might have said something different, which would have made it a second yellow and that wasn’t the case.”

On the performance, Moyes added: “We weren’t at our best for most of the game but I didn’t think there was huge amount between the teams. They had more because of the quality they have got.

“But when I look back at the goals the first one I was disappointed with as it takes a deflection and rolls into Neto.

“The free-kick (for the second) bounces down and settles for Chelsea so I think the run of the ball went in Chelsea’s favour when it was most required.

“Were they better than us? Yeah, I think so – but not hugely better for most of the game.”