Carl Froch believes Anthony Joshua must go after the big hitters and beat Deontay Wilder to become the best heavyweight in the world.
Joshua reclaimed his WBO, WBA, IBF and IBO titles with a comfortable points win over Andy Ruiz Jr in Saudi Arabia.
The win sets Joshua back on course for a unification bout in the future with the winner of Wilder and Tyson Fury's rematch for the WBC crown in February.
And Froch says that Joshua must beat Wilder within his next two or three fights in order to cement his legacy as the top dog in the heavyweight division.
Speaking on Sky Sports Box Office after the fight, Froch said: "He has to now go and become undisputed world champion and that is by winning the WBC title by beating Deontay Wilder.
"Maybe not in his next fight but his next two or three fights and if he does that, there is nothing left for him to do.
"Anthony Joshua has to be up there [as the best in the world] but you can't put him at the top because he is untested against Fury or Wilder.
"They have got to fight each other before you can consider the winner."
After the fight, Eddie Hearn promised Joshua will become undisputed heavyweight king.
“He wants to be the undisputed champion, and he will be. I promise you that," Hearn told BBC Radio 5 Live.
But he is already facing the prospect of giving up one of his belts with the WBO ordering a mandatory defence against Oleksandr Usyk within the next 180 days as the IBF look set to order a mandatory defence against Kubrat Pulev.
That could split the division further, moving Joshua a step away from complete unification of the top division in the sport even if he fights Wilder or Fury.
