Impressed by his range and ease of movement, choreographer Adolph Bolm approached him to appear in a mime role in his ballet production of Le Coq d’Or (1918) at the Metropolitan Opera.
A few years later, Celli moved back to Italy, where he began formal ballet training with Rafaele Grassi, the teacher of Rosina Galli.
He made his Italian debut in a 1922 revival of Manzotti's spectacular ballet Excelsior at Milan's Teatro dal Verme.
The success of his appearance led to a contract with the Teatro alla Scala, where he studied privately under the famed choreographer and dancer Enrico Cecchetti.
[4][5] He also began to choreograph, creating ballets for dozens of operas before he decided to leave Italy, where his position was endangered because of his refusal to join the Fascist party.
He toured for several seasons (1938-1940) as guest teacher with the Ballet Russe de Monte Carlo[6] and then opened a studio on Manhattan's West Side and began a highly successful private teaching career.
In an article published in 1944, Celli stressed the importance of rigorous training: "In all arts success depends upon and demands considerable work.