Chelsea have reportedly hit a stumbling block in their attempts to negotiate a new contract with centre-back Antonio Rudiger.
The German international, who was an important player under Thomas Tuchel in the second half of last season, has entered the final 12 months of his contract at Stamford Bridge.
According to 90min, Chelsea's latest offer made to the 28-year-old fell well short of the defender's expectations, despite requests from his compatriot Tuchel to reward him with an improved deal.
Rudiger's situation is now being monitored by a number of elite European clubs including Real Madrid, Bayern Munich, Paris Saint-Germain, Juventus and Atletico Madrid.
London rivals Tottenham Hotspur, who have previously tried to sign the defender, are the only Premier League club at present who have registered their interest.
Rudiger, who is considering his future at Stamford Bridge, has made over 150 appearances for Chelsea since joining the club from Roma in 2017, winning the FA Cup, the Europa League and lifting the Champions League trophy last season.