A pancake-flat 42 km individual time trial from Viareggio to Massa along the Tyrrhenian Sea, the day after the second rest day — a course made for the pure power men, and Filippo Ganna treated it as a race of his own.
Ganna was fastest at every intermediate split and the margins only grew. At time check 1 (16.7 km) he was already 30 seconds up on Arensman and 32 on Cavagna. By time check 2 (28.9 km) the gap to the next best had ballooned past a minute (Cavagna +1:07, Arensman +1:10). At the final split (38.4 km) Arensman was +1:42 and Cavagna +1:45, the two trading places behind the runaway leader. Ganna stopped the clock at 45:53.
Behind him the day became a Netcompany-Ineos statement: Thymen Arensman set the early standard among the GC men, finished 2nd at +1:54 and produced the single biggest mover of the day, leaping up to 3rd overall. Rémi Cavagna rounded out the podium at +1:59, with Sjoerd Bax and a strong Derek Gee-West filling out the top five.
For the maglia rosa, the stage was a test rather than a coronation. Eulálio, no time-trial specialist, started 2:24 clear of Vingegaard and conceded heavily — 41st on the day at +4:57 — but he had built enough cushion to survive. Vingegaard was the fastest of the overall contenders (13th, +3:00), gaining nearly two minutes but not the jersey. The Giro's only ITT shook the GC hard without flipping it: Eulálio's buffer shrank from 2:24 to 27 seconds.