The Bayern Munich No.1 has kept three clean sheets from his five games thus far as Germany have made sound progress to the semi-finals.
His sweeper-keeper antics have caught the eye throughout the tournament, while he has also made several key saves and Kahn is impressed with his compatriots feats.
"He has proven at this World Cup that he is currently the world's best goalkeeper," he said.
"Everyone knows that he is a wonderful footballer who can really play well. But what is crucial is that in important situations, he can rescue the victory.
"That is ultimately what he will be measured by."
Joachim Low's men take on hosts Brazil in the last four of the tournament on Tuesday.