Seven time Tour de France winner Lance Armstrong has unexpectedly withdrawn from tomorrow’s Milan-San Remo, according to his RadioShack team, due to what it termed ‘acute gastroenteritis.’

“It would have been good to have Lance lineup for the start but we prefer not to take any risk,” said Team Director Johan Bruyneel in a team communiqué, released minutes ago. “It would not be very intelligent to let him start in a race of almost 300 K, while not being healthy.”

Armstrong’s place will be taken by the Japanese rider Fumiyuki Beppu. He will join Daryl Impey, Markel Irizar, Geoffroy Lequatre, Dmitriy Muravyev, Gregory Rast, Sébastien Rosseler and Tomas Vaitkus in the race.

The Texan competed in Milan-Sanremo last year but did not perform as expected. He was dropped on the Cipressa and finished 125th, eight minutes and 19 seconds behind the winner Mark Cavendish.

This season, he has competed in the Santos Tour Down Under and the Volta ao Murcia, with a best placing of eighth in the time trial and seventh overall in the latter. Last weekend, while many of his rivals competed in Paris-Nice, he rode the one day Cape Argus event in South Africa.

Neither Armstrong nor Bruyneel have yet commented on their Twitter feeds in relation to today’s news.

It was confirmed this week that the American would add the Circuit de la Sarthe to his race schedule, lining out in the first stage on April 6th. Before then, he is due to compete in the Criterium International in Corsica next weekend.

That is due to be his first meeting with 2009 Tour de France winner Alberto Contador. The Spaniard has already won two stage races this season, the Volta ao Algarve and Paris-Nice, and is in strong form.

He and Armstrong previously had separate schedules right up until the Tour de France, but Contador unexpectedly added the Criterium International to his race program, creating a direct head-to-head three months early.

It remains to be seen if Armstrong’s stomach problems will force him to drop the French race from his schedule.