"I don't have the words."
That triumph added to an already-glittering palmarés for the 24-year-old, who also has four individual pursuit world titles in the velodrome – as well as the world record in that event – to his name.
No surprise, then, that the Piedmont native is expected to represent Italy on both the road and track next year at the delayed Tokyo 2020 Olympic Games.
Add to that the Paris-Roubaix Espoirs and two stages in the leader's pink jersey in the 2020 Giro d'Italia and you have a star waiting for his time to finally shine on the big stage.
Perhaps sport was always going to be in the young Ganna's future.
"When I was a kid I wanted to have fun, but he made me realise that you need to take advantage of the opportunities, especially if they are once in a lifetime," 'Super Ganna' told the Corriere della Sera.
"He taught me I should go out even when it's cold or raining as I can make the difference when the others are not training," he added.
Growing up in the small municipality of Vignone around 100 km northwest of Milan, the younger Ganna was more into basketball and volleyball as a young teenager due to his height. He did not even his first bicycle until he was 14.
"It was a present from my grandparents," he recalled. "It was green, and at the beginning I hated cycling because I was always crashing!"
Ganna started out on the track, winning the individual pursuit national title in 2015 before going on to take a shock victory at the World Championships in London the following year, which saw him selected for Italy's Rio 2016 Olympic team pursuit squad.
"I unexpectedly became world champion," he said. That put pressure on his shoulders a year later in Hong Kong, defending the rainbow jersey. "I was the big favourite and I was anxious. I couldn't eat, my mind was empty."
Ganna finished second.
"My coach Marco Villa told me: 'Filippo, you're not going to war, relax!' Since then I've faced every race with a philosophical attitude." Ganna regained the title in 2018, and defended it successfully in both 2019 and 2020.
Additionally, he lowered the world record to four minutes, 1.934 seconds during the 2020 World Championships.
Meanwhile, Ganna's road career was blossoming. Multiple time trial wins in the different age groups at the Italian Championships, as well as a big under-23 Paris-Roubaix triumph in 2016, caught the eye of numerous World Tour teams.
UAE Team Emirates gave him his break in the professional peloton, before Team INEOS signed him for the 2019 season.
That year, he won his first World Tour event, an individual time trial stage during the BinckBank Tour, in addition to the elite national time trial title.
Multiple further time trial wins since – including one of the biggest, the world championship – have cemented his spot as a rider on the edge of greatness, ready to take the next step beyond winning time trials and converting them into road race wins. So much so, Italian national team-mate Elia Viviani has nicknamed him 'la bestia' – "the beast".
That first major road race victory came on Stage 5 of this year's Giro, when after spending most of the day in the breakaway, Ganna attacked solo and rode the last 16 km of the stage to victory alone.
So what's next for the man who admits his weaknesses are Nutella – Piedmont's most famous export – and a dinner of steak and red wine?
Unsurprisingly, Ganna has big aims both in the velodrome and on the road.
He has set the last three individual pursuit world records, and wants to be the first man to break the four-minute barrier.
Unsurprisingly, the Giro leader's pink jersey was one of his dreams too. That was accomplished when the world champ won the opening time trial of this year's race, and held on to it for an extra stage.
"(Paris)-Roubaix, (Tour of) Flanders, and the World Championship road race" are also long-term goals along with the Tokyo Games.
"The team pursuit event on the track comes first as I made a promise to my teammates. Then if there's time, I can think about the individual time-trial on the road..."