Vittel, France ? Lance Armstrong remained in third place at the Tour de France on Thursday, scrambling back to the main pack following a punctured tire with about 37 miles left.

Teammate and rival Alberto Contador of Spain stayed in second place and Rinaldo Nocentini of Italy kept the yellow jersey on a day Nicki Sorensen of Denmark won the 12th stage.

“Up and down all day long and was aggressive from the start,” Armstrong said on his Twitter feed.

Sorensen broke away and finished 48 seconds ahead of Laurent Lefevre of France. The 34-year-old Dane spent years as a support rider on Bjarne Riis’s team and this was the first time he won a Tour stage.

“It’s a big thing for me to perform at this level at this age,” he said. “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.”

Armstrong, the seven-time champion, rejoined the main pack after his mishap during the 131-mile ride from Tonnerre to Vittel. He pulled over to the side of the road while his team repaired a punctured back wheel. After a few moments, four teammates helped him catch up.

Teammate Levi Leipheimer, who is fourth overall, fell off his bike nearly two miles from the finish in a crash involving two-time Tour runner-up Cadel Evans. Leipheimer had cuts and bruises on his right wrist, shoulder and back. He hopes to ride Friday.

“My wrist hurts, but surprisingly it’s OK. It could have been a lot worse,” Leipheimer said. “I was a bit surprised by a left corner. … My tire was sliding and I couldn’t quite save my bike from sliding out.”

Armstrong is taking a cautious approach until the three-week race reaches the Alps on Sunday. He said the flat stages were nerve-racking.

“It is stressful with the crashes, on a stage like this where you have nothing to gain and then you lose everything because of a crash or a split in the group,” the 37-year-old Texan said before the start. “You have to pay attention and try to avoid a crash.”

Wednesday’s stage was marred by several crashes and 19 riders were slightly injured.

“Yesterday, there was no way to avoid that crash, if you were just behind it, you were going down,” Armstrong said. “So that is something which keeps you up at night. You have to constantly pay attention. I try to give myself a bit of space from people in front of me so I have a bit of time to brake.”

Riders also learned that an earpiece ban scheduled for today’s stage was overturned, allowing them to communicate by radio with team cars as usual. The ban was in place Tuesday and another was set for the 13th stage before the International Cycling Union reversed itself.