Frossi akaberekerwa muMuzzana del Turgnano, akatanga basa rake semutambi wenhabvu neUdinese, uye, mushure mekugara kwenguva refu muSerie B (naPadova, Bari, uye L'Aquila), akawanikwa naAmbrosiana Inter, kwaakaita kutanga kwake musi wa21 Chikumi 1936, muMitropa Cup. Pashure pacho, Frossi akadanwa kumitambo yeOlympic yezhizha ya1936 naVittorio Pozzo, murairidzi wechikwata chenyika yeItaly, achitungamira timu kuhwina mutambo uyu nemitambo yake yakawanda. Mumakore akatevera, Frossi akatamba neInter kubva muna 1936 kusvika muna 1942, kuhwina mukombe we "Scudetto" kana mukombe weligi, kaviri muna 1938
uye 1940, pamwe chete neCoppa Italia muna 1939. Akarova zvibodzwa 49 mumitambo 147 neInter, makumi mana acho akauya muligi, mumitambo zana nemakumi maviri neshanu. Munguva yeHondo Yenyika II, akazotambawo nePro Patria pakati pa1942 na1943, uye Como muna 1945, asati apedza basa.