Hey, sorry 4 the late reply. Was out all day and even struggled to follow the match...
Always trust your first instinct.
Nope, I believe that Rome match was actually the first time they stepped foot on the same court. They did play in a few of the same junior tournaments in 2017, which turned out to be Sinner's final year of playing any juniors at all, while Musetti was just getting started. But they never actually crossed paths or even trained together, as far as I know.
Musetti went the "traditional" Italian route, playing (and dominating) in national competitions starting basically as a toddler, then some Tennis Europe for U14 and finally the junior ITF tour, where he famously rose to world number 1 after winning the Australian Open. He was always "the chosen one", the brightest star in a country that is historically
Sinner on the other hand was basically this German boy up in the mountains that nobody in the tennis community had ever heard of until age 13. Before that time, he was mostly involved in junior skiing, ranking near the very top of his class in giant slalom and Super-G. Then he committed to tennis, but continued to operate mostly outside the purview of the Italian federation (and dare I say, that may have been his saving grace...). In 2015 he moved to Piatti's academy in Bordighera, began training intensively for the first time in his life, and at 16 dove straight into futures. His junior career was virtually non-existent - never even played a single junior slam, which is virtually unheard of in this day and age.
That nickname came up in the Italian tennis forums around the time of his landmark Bergamo win, when his red/yellow/gray Head kit with the red cap made him look like a 1980s gas station attendant for AGIP (Italy's national oil company, now known as ENI). It also seemed fitting because there was definitely some serious benzina hiding in that scrawny, skin-and-bones figure...
No relation between any of them, even though Alcide Basso is the brother of Marino Basso, who was himself a world class cyclist back in the 70s.
Tennis Basso proceeded to push Cilic to a 7-5 set in that first round, before fading back into low ITF oblivion.