Maurizio Sarri has demanded new deals for Chelsea duo Cesc Fabregas and David Luiz.
Captain Cesar Azpilicueta followed NGolo Kante, Marcos Alonso and Pedro in signing a new long-term contract on Tuesday.
But Blues boss Sarri is still stressing over the futures of Spanish midfielder Fabregas and Brazilian defender Luiz.
Fabregas has only featured in three Premier League fixtures this season and has been strongly linked with a move to Italy in January.
But Sarri is desperate for the 31-year-old to stay at Stamford Bridge, along with Luiz.
He said: I spoke with the club about this one month ago. I know very well it is not easy, but I think we can do a new deal for both.
They are very important players for us. It is very difficult to find a centre-back for this level and it is difficult to find a centre-midfielder technical like Fabregas, so I think they have to stay with us.
The deal is very difficult for this reason (their ages), the club want a short contract and the players want a long contract, it is difficult for this reason but we can find a solution.
Asked whether Fabregas and Luiz were the type of players he wanted to manage, Sarri added: I think David and Cesc are leaders.
I think it is important for me and the staff if they stay with us. I know the difficulties of the new deal.
The problem is only, one or two years for a new contract, but I think the club can find a right solution.
Sarri also commented on Alvaro Moratas struggles at Chelsea. The former Real Madrid striker has netted seven goals this term but his confidence appears shot.
I must understand what he needs, but he has played well in the last month, Sarri said.
He has scored five goals. He needs continuity I think. Confidence, so he needs that with scoring.
Now he is 25, his character is this and he only has to stay calm. In the last match he missed because he wanted to score too much.