Chelsea need to nullify their opponents' aerial threat and avoid conceding from crosses, the Premier League club's manager Mauricio Pochettino said ahead of a trip to Everton.

Chelsea face Everton on Sunday. The Merseyside club's attack will be led by striker Dominic Calvert-Lewin, who is a physical presence and strong in the air.

In recent weeks, Pochettino's side have appeared vulnerable to crosses and have conceded headers in each of their last four league games.

"During the last week we were working on this type of situation," Pochettino told reporters.

"I think two things are important to know. We didn't put pressure on the crosser. Then with the quality of the Premier League that we all have, if the ball is there it is difficult to stop.

"We need to improve. Conceding in this way, maybe I am not showing too much emotion, but I am really upset. We need to work much, much better in these situations."

Pochettino added that midfield duo Enzo Fernandez and Moises Caicedo, signed for a combined fee of just over $276 million, needed to work on improving their partnership.

"They are young. The expectation is massive when you arrive. It's not only the individual expectation but the collective expectation at a club like Chelsea," Pochettino said.

"It is not easy, arriving not in the best place to perform quickly because they need to be part of the solution. They are not the cherry on the cake.

"It's a process, it's going to be a process."