The 25-year-old keeper thinks Schalke should keep their faith in Mathias Schober - who returned to the Veltins Arena in 2007 after starting his professional career with the Gelsenkirchen side in 1994.
Neuer told Bild: "Lehmann was one of my favourite goalkeepers together with Edwin van der Sar.
"However, I have to be honest. I do not think that it would work out well if he joins Schalke.
"I would advise Schalke to have faith in Mathias Schober. He has been at Schalke for several years and has a lot of experience.
"He has always played an important role to keep me on top of my game. He could do the same for Fahrmann."