The Ararat 24-year-old, who is a former Ballarat Clarendon College student, powered through the Italian mountains and attacked on a high-speed descent.

"It's my first WorldTour win so I am super happy," Hamilton said after the 194km stage.

"I just hung on over that final climb and ... when we got back on, I saw my own opportunity and with the speed and momentum we had I was able to get away.

"On paper (Fausto) Masnada is probably faster than me so I was a bit worried about that and tried to make him do the last 500 metres or so and that worked in my favour in the end," he said.

Hamilton moved up to fourth overall, 27 seconds behind the leader, but ahead of 2018 Tour de France winner Geraint Thomas in sixth.

The eight-day race, which was rescheduled from March because of the coronavirus pandemic, ends on Monday with an individual time trial in San Benedetto del Tronto.

The Mitchelton-Scott talent burst onto the scene at least year's Giro d'Italia.

After being held back from the Tour de France, his Tirreno-Adriatic performance shows he will again be a threat when the second Grand Tour event begins next month.

The WorldTour breakthrough follows Hamilton's section in the Australian road race team to contest this year's world championships in Italy.

This is the first time has been selected to represent Australia at elite level.

Hamilton was second toteammate Cam Meyer in this year's Cycling Australia national road race championship at Buninyong.