Petacchi started the season strongly by winning Trofeo Luis Puig and a stage in both Vuelta Ciclista a la Comunidad Valenciana and Paris-Nice. He continued his form going into the Giro. He won his first Giro stage on the first stage, beating the world champion Mario Cipollini in a head-to-head sprint. The stage win also gave Petacchi the maglia rosa. He wore the leader jersey in 5 days and was in all those days inside top 5 in every single stage and won two stages more in the process. He lost the jersey on the first mountain stage in stage 7. He later won three more stages in the race, bringing his Giro stage wins up to 6 stage wins, before leaving the race due to being outside the time limit on stage 18. He then rode Tour de France, where he won 4 stages – three stages in a row, before retiring on stage 7. He wore the green jersey, when he retired. After riding the Eneco Tour, he decided to ride the Vuelta. He won five stages and became the third rider ever, who have won a stage at each Grand Tour in a single year. He finished the season with 24 victories.