Following another frantic battle to get into the early breakaway, it was a massive group that eventually went clear. Notable riders included were stage 12 winner Nico Denz, stage 7 winner Davide Bais, two of the three remaining Soudal - Quick-Step riders plus the likes of Alessandro de Marchi, Derek Gee and Warren Barguil who have all previously come close to breakaway wins at this year's race.
With the best-placed rider in the general classification being
Bruno Armirail at 18:37, INEOS Grenadiers were not fussed about chasing too hard and the time gap quickly grew towards 7 minutes.
Also in the breakaway was Fernando Gaviria, who put his Movistar Team on the front of the breakaway to ensure the pace up the climb was one he could manage.
Surprisingly none of the purer climbers challenged Movistar and after Davide Bais ensured he took maximum points at the top of the climb to put himself back into the lead of the King of the Mountains competition, the break all took on the descent together.
On the flat, the time gap between the two groups extended even further with the break extending their advantage to over 11 minutes with 85km to go.
Unsurprisingly the rain was back in full force on another bleak, Italian day.
With 60km to go the breakaway began to splinter as the attacks started to come. The first to make a move was
Alberto Bettiol. Although he couldn't make it stick, Laurenz Rex made a counter-attack and was followed by Davide Ballerini and Stefano Oldani.
Moments later they were joined by Toms Skujins and the gap began to grow with the breakaway all trying to leave the chase to someone else.
With the men who missed out starting to get organised, the time gap was being held at around 40 seconds. Meanwhile, the gap between break and peloton had grown to nearly 17 minutes meaning Armirail was into the top 10 of the virtual GC.
Refusing to give up on the stage win, Derek Gee was putting in a monumental effort in the breakaway to try and bring the leaders back. Simultaneously Toms Skujins made an acceleration at the front, dropping Rex.
Notably, the time gap to the peloton hit 19 minutes as Armirail began to dream of the Maglia Rosa.
With Rex caught by a chasing group of four riders, including Gee, Denz and Bettiol, the leading trio held a 16 second advantage.
As the leaders went through the 5km to go banner, the time gap went over the magic threshold for Armirail, putting him in the virtual Maglia Rosa.
With the two leading groups combining into the final kilometre, it was Nico Denz leading out the sprint with Derek Gee coming round as quickly. As they both launched for the line a photo finish was required. Denz a narrow winner.
As the peloton rolled in over 20 minutes down, Armirail's Maglia Rosa was confirmed.