Thomas Tuchel insisted Chelsea are "trying their very best" to tie the impressive Antonio Rudiger to a new contract, while also hailing the evergreen Thiago Silva.
Rudiger joined from Roma in July 2017 and has been an integral part of the Blues' backline under Tuchel, starting the most games since the German's arrival last January (50) and ranking first for minutes played (4,575).
However, the centre-back's contract is due to expire at the end of the season, with clubs now able to negotiate with the 28-year-old should he not agree on negotiations with Chelsea.
A host of Europe's elite clubs, including Real Madrid and Bayern Munich, have been linked with the defender but Tuchel remains hopeful his international compatriot will commit his future to the Champions League winners.
Tuchel told reporters on Tuesday: "I cannot predict the future. I don't know if his representatives talk to other clubs. If you know so, or assume so, fair enough.
"It is possible now because it is January and he has not signed yet. As I understand it, we are in communication with him. The club are in communication. He is aware of what I demand, how I appreciate to work with him.
"The level which he is playing is still super high and outstanding. There are no doubts that the situation is a concern for that. The point is very clear, my opinion is very clear. The club is trying the very best and their communication is going on. It has not changed a lot."
Unlike his defensive partner Rudiger, Silva has already signed fresh terms at Stamford Bridge after continuing to impress following his free transfer from Paris Saint-Germain ahead of the 2020-21 campaign, in which he made 34 appearances across all competitions.
The club exercised the option for a one-year extension last season and did so again on Monday, ensuring the 37-year-old will remain a Blue for at least one more campaign.
Silva has made 22 appearances across all competitions this season, with his total of 19 blocks the third-highest by a defender in the Premier League after West Ham's Craig Dawson (24) and Burnley's James Tarkowski (29).
Indeed, no other Chelsea defender has made more than six blocks, and Tuchel credited the Brazil international's efforts.
He added on Silva: "Benjamin Button. Thiago Button of football! I know how much work, how much professional attitude is behind that.
"It is a miracle in a way. He came to this league, this schedule, this approach and intensity of a daily business, in the every end of his career. This was very brave. I know how much effort he puts in to stay fit.
"Off the pitch, at home, he takes care of his recovery and sleep, of his nutrition. This is outstanding. Only because of that this is possible. We are happy because the new contract makes him calm.
"Thiago needs to be calm because he is a very sensitive and emotional person. This makes him very precious for our team and for our dressing room. He can feel emotions, he can feel different state of emotions from others and can help so much.
"He is calm, he has huge targets. He is a big impact, he is available how he needs to be available. When he plays he plays strong, it's a big help. Good for him and good for us."
The defensive duo are set to be in action once more in Wednesday's EFL Cup semi-final first leg against Tottenham, after Tuchel confirmed Trevoh Chalobah and Andreas Christensen as likely injury absentees.
