Chelsea could be headed for a busy summer. The blues have some contract issues to sort at the club. Key players like andreas christensen, Antonio Rudiger and Cesar azipilicueta are yet to commit their future at the club.

Cesar azipilicueta is the club captain. Azipilicueta has won every major trophy at club level at Chelsea. He became the first player for the club to achieve that milestone. Cesar joined Chelsea from Marseille about ten years ago. Antonio Rudiger has been one of the key members in the current Chelsea team.
Rudiger has became arguably the best centre back under tuchel. Andreas christensen graduated from Chelsea academy and was able to establish himself as a key member in Chelsea's senior squad. All these three player could leave the club for free come summer.
Recent reports suggest that Cesar azipilicueta is keen on a move to Spain. 

Azipilicueta has attracted intrest from Barcelona and he could join them in the summer if Chelsea don't match his demands and offer him a new deal to keep him at the club.