The two goalkeepers meet again at the end of the month when Bayern Munich travel to Manchester City in the Champions League, the brilliant Neuer presenting a formidable barrier to the Blues' hopes of reaching the knock-out stages of the tournament for the first time.
And Kahn has no hesitation in naming his fellow German as by far and away the best goalkeeper in the world right now.
"I think Neuer changed the game of goalkeeping in the World Cup," said Kahn who won 86 caps for Germany between 1994 and 2006 and became the only goalkeeper to win the Golden Ball at the 2002 World Cup in Japan and South Korea.
"He was shifting goalkeeping on the next level but we will see what happens in future.
"It's difficult to compare him with goalkeepers of the past because it's difficult to compare different generations, but at the moment he is the best goalkeeper in the world.
"He has all the range of a goalkeeper and is the best in everything he does.
"He's not a goalkeeper, more of a field player, and that's the most difference to the other goalkeepers."
Kahn, speaking at the DohaGoals 2014 forum in Qatar, said Hart remains susceptible to mistakes and that is the main difference between the two men.
"Neuer makes a lot less mistakes than Hart," Kahn said.
"If you look at him there are some games where he plays not very well, Manuel is more on a constant level than Hart.
"Hart needs to be more consistent to be the best."
Manchester City's European hopes are hanging in the balance after losing their group opener in Munich in September and drawing their last two games against Roma and CSKA Moscow.
Manuel Pellegrini's side must beat the Russians at home on Wednesday night to revive their hopes of qualifying for the last 16 but Kahn admits that Bayern - who have won their opening three matches and thrashed Roma 7-1 in Italy in their last group game - would relish the opportunity of eliminating City at the Etihad Stadium.
"It's a big chance for Bayern to put Manchester City out and they will want to do it," said Kahn.
"But if you look at Roma then they are not playing very well, so we will see."
Source : PA
Source: PA