Speaking on Game On on 2FM tonight, Dunphy paid tribute to Man City for their league triumph, but again questioned Guardiola's credentials.
"They are a million miles away from being the best Premier League team ever," Dunphy said.
"Guardiola was hired to win the Champions League like he was at Bayern Munich. He didn't do it there and he is a long, long way from getting a Champions League victory with this team.
"He has to change his philosophy. He has to sign some top class defenders. He has a lot to prove, he really has. He is a good coach but he has a long, long way to go to get to where Ferguson was."
Dunphy then went on to make his bold prediction, jokingly putting his job on the line.
"He hasn't won the Champions League since 2011," he added.
"We will see what he does at Manchester City.
"I'll make a prediction - he'll never win the Champions League again. And if he does, I will resign my position!"