Chelsea risk missing out on Paraguayan prospect Mauro Caballero.

The 17 year-old Libertad striker is wanted by Chelsea and Benfica.

Benfica have made an offer for Caballero and are now waiting on a response. Libertad chief Carlos Guggiari has confirmed an offer has arrived: "Two people representing Benfica gave us a formal proposal.

"We are considering it with the utmost seriousness."