Bettini finished first in the International Cycling Union (UCI) rankings for 2003. He entered the Olympic Games in Athens as the favourite, but the road race was held in extreme heat and it was difficult to predict the outcome. In fact, 69 of the 144 starters did not finish the 224.4km race. Bettini pulled away from the peloton on the 15th of 17 laps, with only Sergio Paulinho of Portugal going with him. The two worked together until the final kilometre. Bettini forced Paulinho to take the lead with 700m to go in order to have a better chance of controlling the final sprint.
Bettini turned around to check the position of the group behind (they were not close) and when he turned back he discovered that Paulinho had risen from his saddle and begun his sprint. Bettini was able to catch Paulinho 200m from the finish and win by one second. Later in the season, Bettini earned his third straight World Cup title.
In 2006 and 2007, he won two prestigious new titles: the world road race championships, which gave him the right to wear the famous rainbow jersey for the whole season! The Olympic Games in Beijing in 2008 were one of the last objectives of his career. Fate decided that his Italian teammate, Davide Rebellin, was leading the competition. Paolo could not beat his partner, and ended the race in 18th place. In September 2008, Il Grillo announced that he was retiring from competition to start a new life.