McEwen, who captured his third stage victory of this year's tour, edged out archrival Stuart O'Grady in a mad sprint at the finish to earn the win with a time of 3:43.14. Americans Fred Rodriguez and Guito Trenti finished third and fourth,
Frenchman Christophe Moreau remains in third overall, but trails Armstrong by 2 minutes and 34 seconds.
Spain's Alejandro Valverde, who had been fifth overall, dropped out of the race midway through the 13th stage because of an inflamed left knee. The Tour goes back into the mountains as the riders head to the Pyrenees Saturday.