September 16 post: As the organizers intended, this year's Vuelta will be decided on stage 20, the final mountain stage with another difficult summit finish.

Stage 20 starts in San Martín de Valdeiglesias, a small town west of Madrid at the base of the Central Plateau. The peloton will head northeast climbing the mountains known as the Sierra de Guadarrama that divide the Central Plateau and the plains in this region. There is one cat 3, two cat 1s and a categoría especial summit finish along the way which means this stage has the same makeup of categorized climbs in the same order as Stage 16. I'm not sure who called stage 16 the Queen Stage, originally, because this stage is equally suited for such distinction and maybe more so given that it's the last mountain stage on the second last day of the race. So lets call this Queen Stage #2.

The cat 1 Puerto de Navacerrada will be climbed twice, once from the steeper north side and then again from the much longer south side (see profiles below). After the second ascent of Puerto de Navacerrada, the route turns east up towards a communications tower/weather station for the final three kilometers of the stage on a climb called Bola del Mundo ("Ball of the World"). These last three km average 12.5%. The road is narrow, kicks up to 20%, is in very poor condition and isn't open to the general public. Bola del Mundo has never been used in the Vuelta before and it has been compared to a famous Vuelta climb, Angliru, and the Giro d’Italia's Monte Zoncolan.

On a stage like this, a 38s 50s deficit doesn't seem like much especially if you claim the 20s time bonus for winning the stage. That's the task Ezequiel Mosquera (left) faces in defeating race leader Vincenzo Nibali (right). This is going to be one heck of a stage. — Steve

‘Bola del Mundo’ latest Vuelta extreme attraction — velonews
Mosquera could snatch away Vuelta a España victory — velonews
Ezequiel Mosquera: “I hope I don’t lose the Vuelta by twelve seconds“ — velonation
  Niebla y hormigón, así es la Bola (climb preview) (01:16 spanish) — rtve.es

Stage 20 climbs
Km 26,1 - Puerto de la Cruz Verde - 5,1 km at 7,06% - Category 3
Km 55,2 - Alto del León - 7,8 km at 6,86% - Category 1
Km 113,4 - Puerto de Navacerrada - 7,0 km at 7,50% - Category 1
Km 150,5 - Bola del Mundo - 21,6 km at 6,26% - Categoría Especial