 Complete the following phrase:  Bertocchi debuted as a mechanic and co-driver alongside Alfieri Maserati in the 1926 Targa Florio. In 1947 he was promoted to the role of chief mechanic and test driver of the Maserati Formula One team, as well as testing road cars like the 5000 GT. In 1957 he ran the car that gave Juan Manuel Fangio his fifth and final world title. Bertocchis only Formula One entry is the 