Jamie Carragher has warned Chelsea that Emi Martinez is not the player he once was after the Blues’ goalkeeper struggled in Sunday’s derby defeat by Arsenal.

Martinez arrived in west London late in the transfer window after Robert Sanchez failed to impress Xabi Alonso in his first start of the season, against Fulham.

His signing was hailed as a statement of intent from the Blues, with the goalkeeper position previously seen as a distinct weak point in the side.

After Sunday’s 2-1 defeat by Arsenal, though, Chelsea have failed to keep a clean sheet in any of their last 19 Premier League games. Martinez did not cover himself in glory for the first goal, scored by Kai Havertz, and had other shaky moments as he was upstaged by his opposite number David Raya.

Speaking after the fact, Carragher made his thoughts on Martinez clear, saying the 34-year-old is a shadow of the player who helped Argentina win the World Cup in 2022.

“What you have to remember with Chelsea bringing this goalkeeper, I think the goalkeeper saves that two or three years ago,” he said, referring to Havertz’s opener on Sky Sports.

“It is better for everyone that Sanchez is not in goal. it is not good for Chelsea, it is not good for Sanchez. He is not quite at the level.

“He’s a good goalkeeper, not a great one, so you go and get someone who has been a great one and some people think he still is. But they are not bringing the goalkeeper that won the World Cup four or five years ago.”

Martinez kept three clean sheets and made some vital saves for Argentina as they triumphed at the 2022 World Cup, winning the golden glove in doing so.

But Carragher remains concerned he is no longer capable of such heroics. He continued: “(Signing Martinez) was not a mistake, they got him for £7.5m, it was a really good deal.

“He is still a really good goalkeeper and he is better than Sanchez. It’ll make everyone feel a little more confident. I always worry with goals like (Havertz’s), it isn’t a mistake, that is just a goalkeeper who isn’t quite as sharp as he once was.

“That is just a goalkeeper not reacting quick enough. Martinez is a very good goalkeeper and he still is a very good goalkeeper, but he’s not the goalkeeper who won the World Cup four years ago.”

Chelsea still have the highly-rated young Belgian Mike Penders in reserve. The 21-year-old will likely get a chance to impress on Wednesday as the Blues host Leeds in the Carabao Cup.