Bellew beat Haye via a fifth-round stoppage at London’s O2 Arena last night.
The Liverpudlian has since called out the likes of Andre Ward and Tyson Fury as he vows to continue his impressive form.
However, Nelson thinks Bellew should seriously considering hanging up his gloves for good.
Bellew, 35, says he has to convince his wife to let him continue stepping into the ring but he has been told he should walk away while he is on top.
“Tony Bellew boxed brilliantly again but I honestly wouldn’t be surprised to see him walk away now,” Nelson told Sky Sports.
“The last fight with David Haye was good but this was a step up.
“His confidence was sky high and we saw that, but we also saw how good he is and how underrated he is. He is not just a brilliant boxer but a brilliant student of the game. “He knows it inside out, mentally, physically and historically, and that goes beyond the repeat win over David Haye.
“Maybe Andre Ward would be the “megastar” he wants next and he mentioned Oleksandr Usyk or Murat Gassiev, once we know who the World Boxing Super Series champion is.
“But does Bellew need to go and take them on? They are not the biggest draws in the world and they are both dangerous, especially for a guy who has spent the last two years as a heavyweight.
“The bottom line is, even Tony Bellew can’t improve on perfection and I think he has achieved it. If it was me, I would walk away. I would not be surprised if he does.”
Meanwhile, Bellew said it would take something ‘ridiculous’ to fight again.
“I’ll be honest, it is going to take something absolutely ridiculous to make me do it again,” said Bellew.
“I mean huge. It is going to have to be massive.
“At this moment in time I am happy with what I have done.
“I have proven everybody wrong once again.”