STAGE 18 is the first of three major climbing days, which will decide the winner of the Tour of Spain.
Time is running out for people to attack current race leader Vincenzo Nibali although Monday will have given them all a lot more confidence.
The race is now arguably between four men. Nibali, Chris Horner, Alejandro Valverde and Joaquin Rodriguez.
Two minutes 29 seconds separate the quartet with Horner now just 28 seconds adrift.
With time bonuses on the line can these four allow a breakaway to get too far up the road.
The stage is a total of 186.5km long and travels northwards from Burgos to Pena Cabarga.
It takes in four categorised climbs. The first three are 3rd Cat, the Alto de Bocos (3km long & 6.6%), Alto Estacas de Trueba (10.9km & 3.2%) and Puerto de la Braguia (6.1km & 6.3%).
The next up is the second category Alto del Caracol, 10.6km and 5.6%.
They will be perfect places to soften up the field and for the challengers to try and isolate Nibali from his Astana team.
However the decisive moves should all come on the final climb.
At 5.9km long it doesn't sound too bad until you look at the gradients that it will tackle.
An average of 9.2% it only has around 1km where the gradient drops below this. And as the riders head under the red kite it maxes out at 20%.
All four are more than capable of handling that type of gradient but for me Rodriguez looks the strongest right now.
He has a habit of riding himself into a tour and he seems to be doing so again. He also has the most time to claw back so I imagine he will be very active on the climb.
If the four look at each other and ignore everyone else then look to the likes of Nico Roche, Domenico Pozzovivo, Thibault Pinot and Leopold Konig could all be involved.
But the top four will want the time bonuses. And if that is the case look to Purito to steal the day.