But on Friday's 12th stage of the Tour de France, the American five-time winner gave with one hand and took away with the other as he took a big step toward securing a record sixth victory in the race.
Armstrong inched closer to overtaking Spain's Miguel Indurain as the Tour's king of kings when he came second behind exciting young Italian Ivan Basso of the CSC team on the first summit finish here to leave main rival Jan Ullrich at over three minutes adrift.
For Tyler Hamilton, Armstrong's former lieutenant who helped him win three of his five yellow jerseys, it was also a bad day on the bike.
Armstrong finished a bike length behind Basso, who two years ago won the white jersey for the Tour's best rider under the age of 25.
Frenchman Thomas Voeckler retained the race leader's yellow jersey but had to work hard to keep it on his shoulders on a day which saw the riders take a soaking as the rain came down before the final 15km climb to here.
The 24-year-old La Boulangere rider, who led Armstrong by 9 minutes, 35 seconds overnight, came in 3 minutes, 59 seconds behind Basso and now leads Armstrong by 5 minutes, 24 seconds in the general classification.
Ullrich admitted he had struggled throughout the day, which left him in 16th place overall at 9:01. Phonak's Hamilton, another pre-race favourite, is 20th at 9:46.
After Armstrong had severely compromised his rivals' chances of victory, he then revealed he had allowed Basso to win because he is helping the Italian's mother in her fight against cancer.
"He's a hell of a good guy. We've been friends for a long time and off the bike we're trying to work a little bit on his mum's situation, to try and see if she can win the fight against cancer," said cancer survivor Armstong, who saw his 55-second advantage over Ullrich grow to 3 minutes, 37 seconds.
"It's pretty special for me to have been out there with him, and the past week we haven't spoke about the race, we've spoke about his mum.
"It was a pleasure for me to let him (Basso) win, and he deserved to win. He was super strong."
During a 197.5-kilometer ride, which included two climbs from Castelsarrasin at the foot of the Pyrenees, the peloton took a soaking as the rains came down ahead of the first climb to the Col d'Aspin.
But despite storms and lightning on the summit finish of La Mongie, by the time the peloton, being led by Armstrong's US Postal team, had reached the foot of the mountain the sun had come out and the roads were dry.
It prepared the perfect scene for one of Armstrong's classic attacks, and after US Postal's pace left Ullrich and Hamilton struggling early on the climb it was not long before the American was up and dancing on his pedals, eventually overtaking Basso's Spanish teammate Carlos Sastre, the winner of the stage at Ax-les-Thermes last year ahead of Ullrich, in the final few kilometres.
Armstrong and Basso then forged ahead, before the Italian overtook Armstrong in the final metres before the finish line.
The 26-year-old Basso, considered a future winner of the Tour, admitted that since he had good legs he simply had to take his chance on a day that proved difficult for a lot of riders, including Ullrich.
"It's the first stage in the mountains, and there's plenty of racing still to be done," said Basso, who picked up his first victory of any significance since 2001.
"It was difficult for a lot of riders, but I had good legs and I just seized my chance. I felt very good, and in any case I had to do well today because of all the good work my team had done for me.
"But Armstrong showed today that he is still very strong."
Ullrich, meanwhile virtually admitted defeat on what was the first test of his strength following his fifth runner-up place last year.
"It was just a bad day for me, but I have to assume it," said the 30-year-old German, who was sweating profusely as he struggled to keep pace up the final climb before arriving in 20th place at 2:30 behind Basso.
Hamilton later claimed he was still suffering from the effects of a crash in the torrid first week of the race, which left him with back injuries.
"I'm still not at 100 percent since the crash last week," said Hamilton, who claimed a great fourth place finish on the Tour last year and won the tough stage to Bayonne despite riding the entire Tour with a fractured collarbone.
"I can't find a good rhythm on the climbs," Hamilton said. "The legs are just not turning right. But the Tour is long, and the time lost today may not turn out to be as bad as it looks. But I can't afford to lose any more."
Saturday's 13th stage remains in the Pyrenees, with several testing climbs including the ascent to the finish, which is rated beyond category.
Top 10 results, Stage 12 (Castelsarrasin to La Mongie, 197.5 km):
1. Ivan Basso (ITA/CSC) 5hr 03min 58sec
(average: 39.0 kph)
2. Lance Armstrong (USA/USP) at 0:00
3. Andreas Kloden (GER/MOB) 0:20
4. Francisco Mancebo (SPA/BAL) 0:24
5. Carlos Sastre (SPA/CSC) 0:33
6. Oscar Pereiro (SPA/PHO) 0:50
7. Denis Menchov (RUS/BAL) 0:59
8. Michele Scarponi (ITA/DVE) 1:02
9. Iban Mayo (SPA/EUS) 1:03
10. Santos Gonzalez (SPA/PHO) 1:03
Stage 12: Complete results
Top 10 overall (after Stage 12):
1. Thomas Voeckler (FRA/BLB) 51hr 51min 07sec
2. Lance Armstrong (USA/USP) at 5:24
3. Sandy Casar (FRA/FDJ) 5:50
4. Richard Virenque (FRA/QST) 6:20
5. Andreas Kloden (GER/MOB) 6:33
6. Ivan Basso (ITA/CSC) 6:33
7. Francisco Mancebo (SPA/BAL) 6:43
8. Jakob Piil (DEN/CSC) 6:53
9. Santos Gonzalez (SPA/PHO) 7:23
10. Carlos Sastre (SPA/CSC) 8:11
Stage 12: Complete overall standings
Stage 12: Category standings