This comes as a huge blow to the Blues as they fight to retain the services of one of their key players.

English Premier League giants Chelsea might be in the headlines due to the sanctioning of club owner Roman Abramovich, but that is not the only crisis facing the UEFA Champions League holders. 

Having won the European cup last season, the Blues remain in the hunt for a second consecutive continental trophy, with Real Madrid standing between them and a semifinal berth. Additionally, while Thomas Tuchel's men are out of the English top-flight title race, Havertz and Co. are through to the FA Cup penultimate round and thus stand a great chance of progressing to the final at Wembley.

However, several of the defenders at the heart of the club's recent success will be out of contract this summer. Thiago Silva and Andreas Christensen will be free agents in a few months, with the latter having reportedly already agreed to join Barcelona. Chelsea captain Cesar Azpilicueta also falls into this category; however, most of the focus has been on Antonio Rudiger and his future at Stamford Bridge.

Tuchel does not wish to see the German center-back leave London for free this summer, having established himself as one of the best defenders in Europe since the departure of Frank Lampard. Unfortunately, the Blues have now received a huge blow in their efforts to extend Rudiger's deal as the player's agent has been spotted in Spain for discussions with a Liga heavyweight. 

Once again, it is Barcelona. According to Sky Sports, Rudiger's adviser and half-brother Sahr Senesie held secret negotiations with the Blaugrana, meeting with the Spanish giants' sporting director Mateu Alemany and his deputy Jordi Cruyff in a restaurant in Barcelona.

The two parties sat down for three hours and while a Camp Nou move is far from being finalized, this is a worrying update for Antonio's current employers. Xavi's side want to sign the German for free come this summer as he is exactly what the head coach desires in a center-back. However, Barcelona aren't the only rivals interested in the 29-year-old.

Real Madrid and PSG are both keeping tabs on the former Roma defender, with both clubs keeping in contact with Rudiger's agent. Additionally, a Stamford Bridge stay has not been ruled out.

One factor that complicates everything for Chelsea is the ongoing sanctions. While the club can stage discussions with Antonio, the London giants are barred from handing him, or any other player or member of staff, a new deal until a change in ownership occurs.