Retired fighter Johnathon Banks believes Daniel Jacobs is the toughest opponent Genandy Golovkin could face at this moment .
Retired fighter Johnathon Banks is now the head trainer for former heavyweight king Wladimir Klitschko .
Retired fighter Johnathon Banks , who is now the head trainer for former heavyweight king Wladimir Klitschko , believes Daniel Jacobs is the toughest opponent Genandy Golovkin could face at this moment .