After three days of sitting back in the main pack while others challenged for stage wins, the worst thing to happen to Armstrong was a small puncture to his back tire on Thursday's 12th stage. Nicki Sorensen, of Denmark, won it, Rinaldo Nocentini, of Italy, kept the yellow jersey, and Armstrong's tire was repaired within a flash.
Finally, today, it's back to serious business as Armstrong goes up against his Astana teammate Alberto Contador on a tricky trek that features one grueling mountain climb.
"Tomorrow is hard, that is a real stage," Armstrong said Thursday. "The climb up Col du Platzerwasel is difficult, it is a long way. It is a longer day and anything can happen."
Armstrong, who retired after his seventh consecutive Tour win in 2005 only to stun the cycling world by announcing he would race again this year, expects some of the Tour contenders to make their move today.
"You have to watch all the rivals, even someone like (Denis) Menchov," Armstrong said of the Giro d'Italia winner. "Some might say he is five or six minutes behind and his race is finished, but if he gains back time, he has the Alps, and then if he is close enough on the (Mont) Ventoux, he could present a problem."
Armstrong briefly looked to be in trouble after about 37 miles on Thursday, when he had to pull over to let his Astana team repair a puncture in his back wheel.
But after a few moments, four of Armstrong's teammates helped him catch up with the main pack again.
"Up and down all day long and was aggressive from the start," Armstrong said on Twitter.
Although Nocentini will keep the yellow jersey heading into today's 13th stage, he is not considered a threat for overall victory -- and seemed to be saying he's done the best he can.
"It's a tough stage tomorrow but I'm already really happy," Nocentini said.
He leads Contador by only six seconds and Armstrong by eight.
A 131.4-mile ride from Tonnerre to Vittel featuring six minor climbs.
WINNER: Nicki Sorensen, of Denmark, who clinched his first career Tour win at the age of 34. After a long breakaway, he surged ahead near the end and finished 48 seconds before Laurent Lefevre, of France.
YELLOW JERSEY: Rinaldo Nocentini, of the AG2R-La Mondiale, team held onto the overall lead by finishing in the main pack with Lance Armstrong and Alberto Contador, of Astana.
QUOTE OF THE DAY: "I'm 34 years old now and it's a big thing for me to perform at this level at this age. I started bike racing when I was 19 and I always hoped that I could maybe go on for many years and I think it shows today that it is possible." -- Sorensen.
NEXT STAGE: Today's 13th stage is a 124.2-mile ride between Vittel and Colmar that features two difficult climbs: the Col de la Schlucht, and the Col du Platzerwasel.
U.S. CYCLIST MIGHT FACE LIFETIME BAN
LAUSANNE, Switzerland --- The World Anti-Doping Agency on Thursday asked the sport's highest court to ban U.S. cyclist Tyler Hamilton for life for doping.
The former Olympic champ accepted an eight-year ban from the U.S. Anti-Doping Agency in June after he admitted taking a steroid in an herbal remedy for depression.
It was Hamilton's second doping offense, which usually triggers a lifetime ban, and he said he would retire rather than fight the case.
The Court of Arbitration for Sport said Thursday that WADA had challenged the American ruling.
Hamilton tested positive for the steroid known as DHEA in an out-of-competition sample taken in February. He later told The Associated Press he took the remedy because he was going through a divorce and his mother was fighting breast cancer.
A CAS ruling on WADA's appeal is expected within four months.