Arsenal and Chelsea are two Premier League sides that desperately need to improve for next season.

The Gunners were extremely disappointing in Arsene Wenger's last campaign at the club.

Arsenal finished sixth in the Premier League and were knocked out in the semi-finals of the Europa League to ensure they will not compete in the Champions League for the second season running.

Chelsea, too, had their fair share of problems.

Antonio Conte's side may have won the FA Cup, but their season can still be considered a failure after narrowly missing out on a top four spot.

Both sides will be itching to get back into the top four next season, but they must improve heavily.

A problematic position for both sides is at centre-back. Arsenal are close to sealing a deal for Sokratis Papastathopoulos, but many will argue they still need another signing to partner him.

Chelsea will also have to replace David Luiz, who looks almost certain to seal a move away after falling out with Conte.

So who will both clubs sign?

According to Sport, both sides have already made a big money move for the same player: Kalidou Koulibaly.

The Spanish publication report that Arsenal have made an offer of €53 million for the Napoli defender, while Chelsea have already bid €60 million.

However, they will have competition from Barcelona.

Blaugrana are said to be working on a player exchange offer for the 26-year-old worth around 40 million euros plus one of Andre Gomes, Paco Alcacer or Denis Suarez.

The centre-back is widely considered as one of the best defenders in Italy, and would undoubtedly strengthen any side he chooses to move to.

But will he even leave?

The Senegalese defender, who is set to play a big role for his country in the upcoming World Cup, admitted last month that he is 'calm' about his future in Italy.

“I don’t know if I’m worth €120m, €50m or €60m, but I laugh about it with my friends,” he told Vosges Matin, per Football Italia.

“That a Senegalese could be worth €120m makes me smile, but it shows Napoli care about me. It’s better to be loved somewhere than hated elsewhere.

“I’m calm, I know that my family are happy in Naples and that my parents are happy to see me in ‘azzurro’. We’ll see what happens.

“People live for football in Naples, my neighbours don’t talk about anything else. When I walk down the street, even the old ladies come to ask me if we’ll win the next game.

“If anyone wants the definition of passion for football, they must come to Naples.”

Would you be happy with the signing of Koulibaly? Have your say by leaving a comment below.