Chelsea's hunt for a new center back took an arrow to the knee on Tuesday, when young Antonio Rüdiger ruptured his ACL in training with the German national team. That's especially terrible news for Roma, who had just taken up the buy-option on the former Stuttgart man's loan contract. For Chelsea, it simply means that the pool of potential signings has been reduced by one. Many other targets remain.
Possibly the biggest name left on the list, certainly at least in terms of physical size, is Napoli center back Kalidou Koulibaly, who's had a very impressive first two seasons for the Partenopei and is now looking to collect his proper reward for that. This rumor had always sounded a bit too suspiciously like the soon to be 25-year-old looking for a better contract, but it would appear that Napoli aren't exactly jumping at the chance to give him what he wants, thus opening the door for others.
"My situation? I have three years on my contract. I was very happy at the time when I signed a five year deal but now I had a great season and I have many offers on the table. I want to make right decision from financial and sporting stand point. Many great clubs want me and I have no news from Napoli. I get the impression I may leave. I want to keep growing perhaps by going abroad. Have I spoken to Conte? No but it could happen, if Napoli doesn't contact me I will start talking to other clubs."
-Kalidou Koulibaly; source: L'Equipe via Gianluca Di Marzio
Chelsea were already exploring a possible €30m bid for the big man and could probably meet whatever demands he would have in terms of wages. If Napoli's dithering, it's time to act.