The Welshman had ridden an impressive opening time trial, putting decent time into all of his GC rivals.
After safely riding through stage two, disaster struck at the beginning of stage three when Thomas crashed in the neutral zone.
The race was held up to allow the 2018 Tour de France winner to rejoin the bunch, having not visited the medical car but dropping back to his team vehicle.
Thomas' injuries sustained on stage three of the 2020 Giro d'Italia (Eurosport)
The peloton then proceeded to make their way towards the summit finish on Mount Etna. But before they'd even started the climb with under 30km to go, Thomas was spotted towards the back of the peloton, with Movistar's Dario Cataldo patting him on the back.
The reason why soon became clear as Thomas slipped out the back of the group, his team-mates Ben Swift and the maglia rosa Filippo Ganna dropping back initially to help him.
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News then filtered through that as Trek-Segafredo took it over on the front of the bunch, Thomas crashed again.
Hovering around 30 seconds in arrears, it looked at one point that Thomas was getting back into the fold as he made his way through the team cars, Trek having slowed the pace to give the Brit a chance, but with 20km remaining he started drifting backwards again, Ganna and Rohan Dennis dropping to keep him company.
Then, on the climb with 13km to go, Thomas was back at the team car, grimacing as he laboured on up the climb, now two minutes behind, before losing another minute with 10km to go, dropping to six minutes with 5km to the line.
He eventually finished the race 12-19 down on the stage winner Jonathan Caicedo (EF Pro Cycling), and over 11 minutes down on the likes of Vincenzo Nibali (Trek-Segafredo) and Jakob Fuglsang (Astana), who finished 51 seconds behind Caicedo. Thomas drops 50 places in GC, now in 53rd place and 11-17 down.
In further bad news for British fans, Mitchelton-Scott's Simon Yates was detached from the peloton with 8.5km to go, finishing the stage 4-22 down. Yates is not cut adrift on GC quite in the same manner as Thomas, and could still potentially fight back as he sits 2-51 on Nibali and 3-46 on race leader João Almeida (Deceuninck-Quick-Step).
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Jonny was Cycling Weekly's Weekend Editor until 2022.
I like writing offbeat features and eating too much bread when working out on the road at bike races.
Before joining Cycling Weekly I worked at The Tab and I've also written for Vice, Time Out, and worked freelance for The Telegraph (I know, but I needed the money at the time so let me live).
I also worked for ITV Cycling between 2011-2018 on their Tour de France and Vuelta a España coverage. Sometimes I'd be helping the producers make the programme and other times I'd be getting the lunches. Just in case you were wondering - Phil Liggett and Paul Sherwen had the same ham sandwich every day, it was great.
