Whakaotihia te rerenga e whai ake nei: I te mutunga o te 1950s i hangaia e Varviso he maha o nga kaitohutohu manuhiri rongonui, tae atu ki te Deutsche Oper Berlin (1958), Paris Opera (1958), me te San Francisco Opera (1959), ko te mea whakamutunga ko tana mahi tuatahi i te United States. I te tau 1958 i whakahaerehia e ia te whakaaturanga tuatahi o te ao o Heinrich Sutermeister "" i te
Te Whakakitenga o te Ao o Brussels. I te 10 o Oketopa 1961 ka hoki ia ki San Francisco ki te whakahaere i te whakaaturanga tuatahi o te United States o Britten's "A Midsummer Night's Dream". I whakahaerehia e ia a "The Marriage of Figaro" mo tana mahi tuatahi i te Glyndebourne Festival i te tau 1962 whai muri i te mahinga o "Der Rosenkavalier" mo tana timatanga me Covent Garden i tera tau. He maha nga wa i hoki mai ai ia ki te Royal Opera puta noa i te toenga o tana mahi, e whakahaere ana i te raarangi whanui mai i nga mahi paerewa a Mozart, Puccini, Strauss, me Wagner, ki nga opera iti ake e mahia ana penei i a Debussy's "Pelléas et Mélisande".