What's the stage like?
It's a flat, 15.7km time trial on wide roads. It's largely straight, too, with only a handful of corners that will require careful navigation.
Who are the favourites?
Filippo Ganna (1.402/5) has dominated the two time-trials so far on this year's Giro, and there's every likelihood he will do so here. He has been supreme all season, too: winning the World Championships at Imola the week before the Giro started, and comfortably bettering most of his rivals here when he faced them on Stage 8 of Tirreno-Adriatico.
Odds of 1.402/5 might seem short on any rider at the end of three hard weeks of a Grand Tour, but with Ganna, that price looks value: it seems like only a miscalculation or accident can deny him his fourth stage win.
Who are the most likely outsiders?
Rohan Dennis (7.006/1) was second to Ganna on Stage 14 and has shown in the mountains in recent days that he is in sparkling form. His super-domestique dedication can't have been the best preparation for an all-out time trial effort, though, and whilst he will no doubt put in a good performance, it's hard to see him troubling Ganna.
Victor Campenaerts (8.6015/2), the current hour-record holder, is omnipresent at the front end of time trials, but he was more than two minutes down on Ganna on Stage 14 and it's hard to see him turning that around.
Elsewhere, cases can be made for Brandon McNulty (40.0039/1), Thomas De Gendt (50.0049/1), Josef Cerny (14.0013/1), Mikkel Bjerg (30.0029/1) and Joao Almeida (50.0049/1), but for any of these riders to win, calamity would need to befall those at the top of the market.
What effect will it have on the overall market?
It will decide the Giro.
The dramatic outcome of Stage 20 - Tao Geoghegan Hart beating Jai Hindley - has meant that the riders are equal on time going into this final stage. Hindley will wear the Maglia Rosa - courtesy of some milliseconds gained somewhere over the three weeks - but Geoghegan Hart is favourite (1.251/4) to have wrestled it from him by the day's end.
It's hard to assess just how much Geoghegan Hart is likely to have in hand over Hindley. Geoghegan Hart was 49 seconds down on Hindley on Stage 1, up by over a minute on Stage 14, and up by six seconds on a flat 10km at Tirreno-Adriatico earlier in the season.
Going back to the 2018 Vuelta a Espana, they shared the honours - Hindley was quicker on the first time trial, Geoghegan Hart on the second.
On balance, Geoghegan Hart's experience, team set-up, and slightly easier ride on Stage 20, gives him the edge over Hindley, but I won't be weighing in at 1.251/4.
Because if we learnt anything from the Tour de France this year, it's that anything can happen in a deciding time trial.
*Odds correct at the time of writing