He first worked in Vienna and was Generalmusikdirektor (GMD) of the Royal Swedish Opera. He conducted world premieres such as György Ligeti's "Requièm", Karlheinz Stockhausen's "Carré", and Bernd Alois Zimmermann's opera "Die Soldaten" and his "Requiem für einen jungen Dichter". He directed the Frankfurt Opera from 1977 to 1987. During his era, the company became one of the leading operas.