i don't know, but we were always told then that it was his first performance (the one in chicago); that was a festival for the benefit of the then Chicago Ballet, and wasn't connected with Geneva.
I tried some googling and found a site that lists this:
"1977: Title role in The Prodigal Son (Balanchine), International Dance Festival of Stars, Chicago"http://img2.browsebi...aryshnikov.html
But who provided the ensemble for him, even assuming he only did excerpts? Perhaps that's where the Geneva Ballet came in.
Another interesting tidbit on that list:
"1974: Title role (cr) in The Prodigal Son (Murdmaa), Baryshnikov Choreographic Evening, Leningrad"
I remember from some biographical reports that he staged one of these special evenings (a one-time-only performance) in the spring before his defection. If that list is accurate, then it appears he had some serious interest in this role, even by a different choreographer! (Who is Murdmaa? Did he "borrow" the Balanchine version?")