Armstrong appears unstoppable in his quest to become the fifth man in history to win the prestigious race four times. The American easily retained the overall yellow jersey by finishing ninth in Tuesday's stage and crossing the line just in back of Joseba Beloki, who remained second overall.
Botero made Tuesday's 140.43-mile race from Vaison-la-Romaine to the ski station of Les Deux-Aples -- the longest stage of the
Tour -- in five hours, 55 minutes and 16 seconds.
Botero, also the winner of the ninth stage, improved to seventh overall.
Mario Aerts of Belgium was second in the stage, 1:51 behind. Raimondas Rumsas of Lithuania is third overall, 6:39 behind Armstrong.
Igor Gonzalez Galdeano, who wore the yellow jersey until Armstrong took over in last Thursday's opening mountain stage,is fourth, 8:50 back.
With five stages left, Armstrong is in prime position to ascend to the upper echelon of cycling royalty. He is looking to join France's Jacques Anquetil (1961-64) and Bernard Hinault (1978, 1979, 1981, 1982, 1985), Belgium's Eddie Merckx (1969-72) and Spain's Miguel Indurain (1991-95) as the only cyclists to win the great race more than three times.
Armstrong already is recognized as one of the world's most courageous athletes after battling back from life-threatening testicular cancer to capture the 1999 event. In 2000, he cemented his place among cycling's all-time greats, becoming the first American since three-time champion Greg LeMond (1986,
1989 and 1990) to claim back-to-back titles.
Wednesday's 16th stage is a 111.536-mile trek from Les-Deux Alpes to La Plagne. The Tour finishes Sunday on the Champs-Elysees.