"In the 2003 Tour de France, Lance Armstrong was riding with Iban Mayo at the start of the climb to Luz Ardiden when Armstrong crashed, bringing Mayo down with him. The fall was caused when Armstrong caught the handlebar of his bike on the strap of a spectator's bag. Jan Ulrich, who was riding just behind Armstrong and Mayo, avoided the crash, and in an act of chivalry he slowed to wait for the fallen riders. Armstrong quickly re-mounted his bike and caught Jan Ulrich. Immediately, Armstrong attacked the group of riders, none of whom could follow him and he powered his way to win the stage by 40 seconds."
From Strava:Back in 1985, the year Luz-Ardiden was introduced to the Tour, this climb saw a battle equally dramatic. But this time drama ensued not because someone attacked, but because someone didn’t, and was told not to. The directors of his La Vie Claire team ordered Greg Lemond, who was in position to attack and win the tour on the slopes of Luz-Ardiden, to sit up and wait for his ailing French teammate and current leader of the race, Bernard Hinault, whom they said was very close behind. Lemond soft pedaled and waited, and waited, and watched his dream of winning the tour disappear.
It turns out that Hinault was more than 3 minutes behind Lemond. Lemond was enraged, because he was clearly stronger than Hinault that year and could have easily won the tour to become the first American ever to win the race. After that stage, a deal was made that that if Lemond continued to help Hinault win one more time in ’85 (his fifth victory), the Frenchman would help Lemond win the following year in 1986.
Hinault did not live up to his word and attacked Lemond in the ’86 tour on the road to Pau (also in the Pyrenees). Lemond was forced to counter attack and Hinault had no answer. Lemond finally won his first Tour de France as the first American victor in 1986.
Watch this video showing Lemond and Hinault on Luz-Ardiden in 1985, which pitted the teammates against each other as adversaries.