 Complete the following phrase:  Coulthard began the season by scoring points in four of the first five races. Before the San Marino Grand Prix, Klien was replaced by Red Bull test driver Vitantonio Liuzzi who partnered Coulthard for the next four races. The forced withdrawal of all teams using Michelin tyres, including Red Bull, at the controversial United States Grand Prix, meant Coulthard did not start a race for the first time in his career. In July, it was announced that Coulthard would remain at Red Bull for 2006. This marked a turning point in his season as Coulthard did not score points in six of the nine remaining races. He achieved points three times during this periodin Germany, 