Already one kilometer after the start, Benoît Joachim raced away from the field. After about 100 kilometers, shortly after the first mountain standing which Joachim won, he was captured by the field. Twenty-six kilometers before the end, and following an attack by "Gibo" Simoni, Ivan Basso raced away with only very few riders able to keep up. Only Paolo Savoldelli, who had picked up a twenty seconds advantage on the descent and therefore was able to reserve strengths, could stand Basso's rhythm, and he beat the Varesian rider at the summit of Zoldo Alto. Simoni came up 21 seconds later, but defending champion Damiano Cunego lost around six minutes and was ruled out from the list of contenders.
Alessandro Petacchi's efforts during winter, striving to gain ability in the mountains, paid off just as they had done in Milan–San Remo, enabling him to recover from the gruelous Dolomiti stage far better than any of his opponents, and the Italian from Fassa Bortolo sprinted to his second victory in this Giro.
ColombianIván Parra won the stage in St. Ulrich by breaking ahead of his fellow breakaways on the previous climb. Spaniard Juanma Gárate, fourth in the 2004 Giro d'Italia, came in second. As for the GC, Ivan Basso, with gastrical problems, lost one minute and the maglia rosa to "Il Falco" Paolo Savoldelli.
It was in this stage that Ivan Basso's illness was really going to take its toll. Upon the first gradients of the Stelvio Pass, Cima Coppi of this edition, the Team CSC rider was left behind and unable to react because of his health problems. He lost eighteen minutes to the other GC riders. Savoldelli lost time to Simoni and Di Luca, who arrived in Livigno 3' 15" later than Iván Parra, scored an impressive Dolomiti double.
This stage, originally 205 kilometres long, was reduced to a length of 147 kilometres due to bad weather conditions at Forcola di Livigno, one of the mountain climbs that the peloton had to go through that day. Alessandro Petacchi, after the abandon of sprinters such as Baden Cooke, Robbie McEwen, Stuart O'Grady or Jaan Kirsipuu, had only Erik Zabel to challenge him, but the Italian's speed was too much for the veteran T-Mobile rider.
After the second rest-day, the peloton did not want to spend too much energies on a flat stage, so it was easy for a break-away of eighteen men to gather an advantage of 10 minutes. Amongst these breakaways, there was Crédit Agricole rider Christophe Le Mével, who outpowered his fellow breakaways to notch up his first pro victory.
