Top riders Alejandro Valverde (Team Caisse d'Epargne), Carlos Sastre (Cervelo TestTeam) and Bradley Wiggins (Team Sky) will all miss today's Amstel Gold Race because their flights to the Netherlands were canceled because of the volcanic ash clouds disrupting aviation across Europe.

The disruption has affected hundreds of thousands of travellers since Wednesday, when the Eyjafjallajoekull volcano in Iceland began erupting.

The withdrawals were a further blow to the one-day classic after Team RadioShack's Lance Armstrong and Fabian Cancellara of Team Saxo Bank decided not to take part in the race through the hills around this southern Dutch city.

Race organizer Leo van Vliet told Belgian broadcaster VRT on Saturday that Valverde was considered one of the pre-race favorites.

Van Vliet said "there's nothing you can do about it."

Cancellara decided against racing after winning last week's Paris-Roubaix and the Tour of Flanders a week earlier.