[3] After the death of Wieland Wagner in 1966, he took care of his artistic legacy, in productions in Bayreuth and on tours to Italy, France, Japan, and the US.

[4] He remained to be invited as a guest, directing performances in Essen, Frankfurt, Stuttgart, Amsterdam, Basel, Milan, Paris, Venice and Chicago.

He also directed Lohengrin, Die Meistersinger von Nürnberg and the Ring cycle, and he engaged other directors for more stage works by Wagner.

He had a strong sense for talent, giving singers such as Renate Behle, Johannes Martin Kränzle and Rainer Trost and director Herbert Wernicke the foundation for an international career.

He directed Aribert Reimann's Troades, Bernd Alois Zimmermann's Die Soldaten,[2] Zemlinsky's Eine florentinische Tragödie, Henze's König Hirsch, Alban Berg's Wozzeck, Pfitzner's Palestrina and the world premiere of a commissioned chamber opera by Xaver Paul Thoma, Draußen vor der Tür after Borchert's play.

[7] Lehmann invited guests to direct other rarely played works from the period, for Wolf-Ferrari's Sly, Berg's Lulu, John Corigliano's Die Geister von Versailles, Reimann's Das Schloß, Martinů's Griechische Passion, Britten's Billy Budd, Ligeti's Le Grand Macabre and Schoeck's Penthesilea.

[4] In 2000 Lehmann directed the world premiere of Volker David Kirchner's Gilgamesh, commissioned for the Expo 2000, with stage design by Ekkehard Grübler and conducted by Stefan Sanderling.