Lehmann has just lost his coaching job with the Gunners.
Leno told arsenal.com: "When I was a child, Iker Casillas was always my idol, but when I was at Stuttgart, there were many players, like Timo Hildebrand and Jens Lehmann. I watched many of Jens' training sessions to learn from him. So yeah, they were my idols.
"I had some training sessions with him when I was very young, about 16 or 17 years old. Jens Lehmann was around 40 years old and for me it was very exciting. He was so concentrated, so professional and that's the mentality that you need as a professional goalkeeper."