Mathieu van der Poel won the junior men's world road race title after an impressive solo attack.
The 18-year-old Netherlands rider, who had already won the world junior cyclo-cross title earlier this year, bridged across to breakaway rider Franck Bonnamour, of France, on the last of five laps of a 16.6km finishing circuit around Florence and then surged clear on his own to seal a three-second victory.
Denmark's Mads Pedersen won a reduced-bunch sprint for the silver medal, with Albania's Iltjan Nika claiming bronze.
Scott Davis was Great Britain's highest finisher, in seventh place, but Tao Geoghagen Hart, who had been hoping to challenge for a medal, crossed the line 118th after snapping a chain while well-placed in the field and being forced to wait for a replacement.
Davies said afterwards: "It would have been nice to get on the podium but I can't complain at that to be honest."
Junior men's road race result
1 Mathieu van der Poel (Neds), 3:33:14
2 Mads Pedersen (Den), +3secs
3 Iltjan Nika (Alb), same time
4 Logan Owen (USA), st
5 Lorenzo Rota (Ita), st
6 Lucas Eriksson (Swe), st
7 Scott Davies (GB), st
8 Artem Nych (Rus), st
9 Sergey Shemyakin (Kaz), st
10 Benjamin Brkic (Austria), st