Ben Chilwell, a defender for Chelsea, has acknowledged that finding a replacement for Antonio Rudiger this summer will be "tough" for the Blues.
Rudiger, according to Chilwell, was one of the Chelsea team's most important players last year.
After his contract with Chelsea expired, Rudiger just completed a free transfer to Real Madrid.
Chelsea must now find a suitable successor for the German international because they were unable to persuade him to extend his stay at Stamford Bridge.
The west London club has been linked with a number of new center backs, but it will be difficult to find someone with Rudiger's presence.
Of course, it will be challenging to replace him, Chilwell said, according to Football London.
"Toni was one of the team's most important players last year, and not just because of his incredible on-field performances every single time.
"I only have positive things to say about Toni. He ensures that everyone maintains their standards on the practice field and in the locker room before games. I've already informed him that I wish him the best of luck in his upcoming chapter. He then wished us luck and continued.
"I believe Chelsea will hold a special place in his heart forever. But good luck to him; moving to Madrid was probably his dream.