Before beginning the Tour, Merckx won the men's road race at the Belgian National Road Race Championships. Merckx won the Tour's opening prologue to take the race's first race leader's yellow jersey. After losing the lead following the second stage, he won the sixth stage after forming a breakaway with Lucien Van Impe and regained the lead. After expanding his lead in the stage nine individual time trial, Merckx won the race's first true mountain stage, stage 10, and expanded his lead to five minutes in the general classification. Merckx won three of the five stages contested within the next four days, including a summit finish to Mont Ventoux, where upon finishing he was given oxygen. Merckx won two more stages, both individual time trials, and won the Tour by over twelve minutes. He finished the Tour with eight stage victories and won the mountains and combination classifications. The eight stage wins equaled the previous record for stage wins in a single Tour de France. Merckx also became the third to accomplish the feat of winning the Giro and Tour in the same calendar year.